You know the story of Lady Georgiana Spencer, the Duchess of Devonshire, who is well-known for her public affair and pregnancy. However, her sister Lady Henrietta Bessborough's story was just as scandalous.

Its 1794, and Henrietta is now in her thirties, mother to several children, but in a loveless marriage. On a chance meeting in Italy she meets the handsome Lord Granville, who is 12 years her junior. Thus starts the beginning of a torrid affair that spans decades.

Under his spell, she pines, lusts and sacrifices to be with her young lover. All-consuming, she knows they can never be together but risks it all just the same.

This is a fabulous historical fiction that plunges us into the regency period, into the heart of society. Henrietta is an unusual protagonist right from the beginning. Not as beautiful as her sister and always sickly, she doesn't scream a heroine, but I suppose that's the point. Hadlow has a knack for writing these under-dog's story - like Mary Bennett's story in The Other Bennett Sister.

I personally found it hard to understand her motivations a lot of the time, where she should show strength, she languishes and shows no self-control, on the verge of being rather pathetic and obsessive. However, in her weakness she also shows strength and resilience, which is the juxtaposition of her life.

An.avid follower of politics and one of the spear heads of regency society at the time, she is an interesting character to learn more about, and I am glad I had the chance.

Favourite quote(s):
"I could never understand a medium in love, I must love with my whole heart and soul, my whole existence, know no happiness or misery but from the object of my passion."


Rating:
⭐️⭐️⭐️💫/5

Calling this a love story doesn't fully capture the essence of this book, which details Lady Henrietta Bessborough's long affair with Lord Granville. Hadlow skillfully builds the narrative from limited information about Harriet, highlighting how her love for Granville profoundly shaped her life, even leading to devastating consequences. Like many women of her class, Harriet indulges in gambling, socializing, and seeking pleasure, but her deep love for Granville changes everything. Despite his pleas, her societal position prevents her from leaving her marriage, keeping them apart. Harriet's life seems marked by brief happiness and much sorrow, enduring illness, estrangement from her illegitimate children, and a strained bond with her sister.

Although categorized as fiction, the book feels more like a biography, with Harriet as the narrator. While I enjoyed the story, I occasionally found Harriet frustrating as she shifted between being a strong woman and acting like a lovesick teenager. Perhaps this reflects how women of her time navigated societal expectations, where respectability stemmed from marriage. With thanks to Netgalley and the publisher for a copy of an arc in exchange for a review.

This book tells the story of Lady Harriet Bessborough, who was unhappily married to Lord Bessborough. Despite bearing him four children, he was abusive and would berate her publicly and behind closed doors. It was safe to say that she lived in fear of her husband, especially when he was drunk.

Trapped in a loveless marriage, in 1794, when she was 33 years old whilst recuperating in Naples, she met Lord Granville Leveson Gower. He was terribly handsome and twelve years her junior.

Harriet tried to resist the temptation of an affair with Lord Granville, but he relentlessly pursued her.

This was the beginning of an exciting, but also sad journey for Harriet…

I really felt for her as I was reading this book. She felt powerless in her marriage, and she was her husband’s possession. She knew that if she left Lord Bessborough, he would keep their children, and that was something she would never give up. Despite an unhappy marriage, she resolutely loved her children.

Harriet deeply loved Granville, probably more than he loved her. She had the wisdom of an older person, and she knew that the affair would never last.

This book is a portrayal of what life for women was like back in the 18th century. At times, I was angry at Harriet (but more so at Granville), and then I felt deep sadness for her precarious situation.

I definitely recommend it.

Many thanks to Mantle for approving my NetGalley request.

I knew a little bit about the Countess of Bessborough, so was interested to read the fictionalized account of her life.
Harriet is an emotional and intelligent woman.
The book explores her complicated marriage that served it's social purpose but leaves her trapped and unsatisfied, and her passionate affair with Granville Levenson-Gower.
The book is told entirely from Harriet's point of view and I did find her constant self-reflection a little slow at times.
Hadlow does an excellent job of recreating the period with lots of historical details - so much research must have gone into the writing of the book.
The blending of the real and fictional is very well done. Harriet is very much a woman of her times and despite her intelligence, is surprisingly passive, which highlights the challenges do society women of the period.
The definitely made me want to research and read more of the real stories behind the characters.

I really enjoy historical novels and this one did not disappoint. I found it interesting to read about this era and there were many high profile figures featured in the story. It confirmed my thoughts that women through the centuries have had to contend with double standards from their menfolk and had little choice in their marriage partners. Lady Harriet Bessborough found herself in a loveless marriage and embarked on several affairs. This book tells the story of her final love affair with Lord Granville, more than ten years her junior who she considered to be her soulmate. Her position as his mistress told from her point of view showed how little control even female members of the aristocracy had over their life. Clearly it wasn’t just their husbands who were happy to embark on affairs though for the women the stakes were high if discovered and their husbands chose to divorce them. This was not the most uplifting of stories at times but it was well researched. Thanks to NetGalley and Pan MacMillan for an advanced reading copy in return for an honest review.

Enjoyable historical fictional! Following along Harriet and learning more about the ear was fun to read!

Janice Hadlow's "Rules of the Heart" is a riveting historical novel that whisks readers away to late 18th-century England, a land of social conventions and aristocratic intrigue. Based on actual historical figures, the novel tells the life of Lady Harriet Bessborough, a woman who, though born into privilege, is dissatisfied with her loveless marriage. Her desire for something more sends her into a passionate, and illicit, affair with the scandalous rake, Lord Granville.

The novel beautifully examines the tension between duty and desire. The writing of the author is lyrical and engaging, conveying the rich world of the aristocracy while exposing the emotional chaos behind the veneered exterior. Readers will be captivated by Harriet's path as she jeopardizes her reputation and standing in society for a love that guarantees happiness as well as destruction. The novel is a riveting and exquisitely written story of love, gossip, and tough decisions made by women in a society where their hearts were not often their own.

2.75/5 stars.

Considering 'The Other Miss Bennet' is one of my favourite books that I've read in 2025, I was eagerly anticipating Janice Hadlow's second novel. I will admit that I went into it a little bit blind. The synopsis is suitably vague, but in a nutshell, it explores the affair between Lady Harriet Bessborough and a younger man, Lord Granville. Which seems to be ample fodder for a novel, one has to admit. 'Rules of the Heart', however, is something of a misfire.

It feels like a stretch to call this a novel, because what it really is is a docu-drama in prose. Hadlow does have a background as a historian and in this instance, it's to the book's detriment. The author takes such a completely detached approach to its central topic that on several occasions, I had to remind myself that I was reading a novel, not a work of non-fiction. I also believe one of this book's key downfalls is that Harriet and Granville - who are real people - are rather dull. The book dedicates itself to fictionalising real events, so you feel endlessly trapped in narrative deja vu, watching the same things happen over and over again while the central couple barely get any time together. When they do, it all feels rather clinical and detached. Moreover, Hadlow's need to end almost every chapter with a vague cliff-hanger about oncoming horrors grated on me endlessly.

As a protagonist, Harriet was rather passive. The novel is written in first person and I found her girlish and silly. It all comes across as though she's telling us her life story. For a woman who is in her thirties and forties through the book, it was like reading the thoughts of a teenage girl for all the wailing and waning she did. Barely driving the action - barely leaving the house! Her husband is also just conveniently not there and their affair is an open secret, so the stakes are insanely low. Her entire life and thoughts are completely ruled by two rather unimpressive men, despite the fact that she clearly has a brain. A quote from the Dowager Countess of Grantham comes to mind...

This is a biography masquerading as a novel. I suggest trying Hadlow's first book over this one, it's a much stronger offering.

I have always loved historical fiction so to be able to read this book through NetGalley I was excited.

Following the life of Harriet and her long love affair with another member of the Nobility, the author gives a real insight into the struggles women of that time would have faces, From loveless marriages to illegitimate children, those women had to do what it takes to survive and Harriet was no different.

Although I enjoyed the book, I only gave it 4 stars as I found some of the characters very difficult to like - but maybe that is the author’s intention?
I loved learning about Harriet’s life and it left me intrigued to learn more of this era.

this book was long, classic-feeling and painfully romantic! the seventeen-year long love affair between Harriet and Grenville took me a little while to get through, but I loved this 400 pages of passion, joy, guilt and despair as Harriet tries to hide her affair (and her illegitimate children!) from her husband, and from wider society. Harriet's guilt twinned with her obsession with Grenville is excruciatingly gripping, and I never once left the feeling of fear that she was going to be found out, publicly denounced and shamed.

Rules of the Heart is a rich and elegant work of historical fiction that captures both the glitter and the peril of late eighteenth-century society. Lady Henrietta Bessborough, in her thirties and well-versed in the conventions of the Ton, knows that discretion is essential for a married woman who seeks the company of a younger lover. But when she meets Lord Granville, twelve years her junior, her carefully maintained composure crumbles. What begins as a calculated affair soon becomes an overwhelming passion that threatens to destroy her reputation, her security and her sense of self.

Janice Hadlow evokes the period beautifully, with vivid descriptions of society’s expectations and the rigid rules that govern desire, appearances and scandal. At the heart of the book is Henrietta herself, portrayed with nuance and sympathy. Her emotional vulnerability and her longing for love make her both compelling and tragic, as her choices pull her deeper into a world where passion comes at a heavy cost.

The relationship between Henrietta and Lord Granville is written with intensity, giving insight into the motivations and risks behind a love affair that defied convention and endured for seventeen years, producing two children. The book succeeds in showing how love, desire and societal judgement can collide in ways that are both deeply human and devastating.

This is a captivating and emotionally resonant book that blends romance, history and scandal into a story that lingers long after the final page.

Read more at The Secret Book Review.

I found this an interesting story, clearly based on very detailed research, which offered many insights into the difficulties faced by women in the past due to the restrictions placed upon them by societal norms. It raises questions about how different Harriet Bessborough’s life might have been if she’d been free to follow her passions, secure in the knowledge that her children and wider family wouldn’t be embarrassed by her love for Lord Granville.
Oddly, it didn’t entirely work for me as a novel. I struggled to engage with the characters on an emotional level, and I found it slow going. The first few chapters in particular almost put me off continuing, but I was interested enough in Harriet’s life to read on. Ironically, the author’s note at the end suggests that her love affair with Granville is not the most interesting part of Harriet’s life, and the novel’s in-depth focus on this barely does justice to her courage and endurance.

This historical novel tells the story of an eighteenth century noble woman’s two decades love affair with a younger man, also of noble birth. Harriet Bessborough was the sister of the Duchess of Devonshire, of Chatsworth House fame. Like many women of noble birth at this time, her marriage to Lord Bessborough was a transactional affair, with both parties living largely separate lives after Harriet fulfilled her duties of producing heirs. Prone to ill health, she was convalescing abroad when she met Lord Granville, a dazzlingly handsome man twelve years her junior. The novel gives a credible account of the lives of the English nobility in the years after the French Revolution and the Napoleonic era, including the adulterous affairs of both sexes and the challenges of concealing illegitimate offspring from husbands and households. A fascinating and compelling account of aristocratic life during a volatile and uncertain political era.

Thanks to NetGalley, the author and the publisher for the opportunity to read and review this book.

With thanks to the publishers and NetGalley for an advance review copy.

Georgiana, Duchess of Devonshire, has been on my radar for years, long before I moved to Derbyshire with all its associations with her. So I was intrigued by the idea of this novelisation of her sister Lady Harriet Bessborough's life and specifically of her affair with the much younger Lord Granville. Sadly, the book's description did not live up to the reality.

The narration is in the first person, and Lady Harriet reveals herself to be an indecisive, immature woman who in her wishy-washiness risks destroying not only her own life and reputation but those of her close family. In her late 30s, having been a society wife in an admittedly loveless marriage for nearly 20 years (but most upper-class marriages were at the end of the 18th century), she is bowled over by a good-looking and persistent young man who flatters her into being ready to throw away her position, security and reputation for the sake of her hormonal instincts. Am I being harsh? I do have sympathy for the very real and powerful attraction she is in thrall to, but she is also a woman with agency to make choices. It is her abdication of this agency which irritated me so much - she dithers, and flip-flops, and says far too many things she doesn't mean, and illudes herself to the point where I just wanted to smack her. I did not finish the book I'm afraid - I just could not sympathise with her enough. If you think grand-gesture, all-consuming, hugely ill-advised love affairs are the ultimate in romance, you'll love this. Otherwise, I'd advise you to steer clear.

I do love a Janice Hadlow story and this is no exception.

Here we have the story of Harriet. It is 1794 and she is unhappily married to Lord Bessborough so she can be near her dear sister, Georgiana. Lord Bessborough is a cold and unkind man, beating Harriet when he is angry about something she has seemingly done that has displeased him. With Lord B she has a glittering social life but she is missing the one thing that she craves above all else: True love. In an effort to find this love, Harriet embarks on a number of affairs leading Lord B to threaten her with divorce.

Divorce would mean being separated from her dear children and would bring about her social ruin. However, Georgiana and her husband, Lord Devonshire, step in and make it clear they would side with Harriet. Lord B backs down but warns Harriet that her behaviour won't be tolerated and, should he get wind of another affair, he will not be prevented from seeking a divorce in future.

However, Harriet falls ill and accompanies her sister Georgiana to France, Switzerland and finally Italy, to recover and recuperate. It is here that Harriet meets and falls hard for the dashing and handsome Granville Leveson-Gower. Granville is 12 years her junior and has had a number of wild affairs himself. It is clear that Granville is attracted to Harriet and pursues her aggressively, dismissing her worries about the age gap and what would happen should her husband find out. Harriet is helpless in the face of Granville's pursuit and they embark on a passionate affair...but can they survive it?

This is a beautifully told, richly detailed story based on true events. Hadlow is an accomplished writer that puts me very much in mind of Jane Austen. The characters are richly drawn and real. At times I wanted to shake Harriet for being so silly, and at others I wanted to cry with her as I felt her pain and fears. This is a well researched book as I spent some time reading up about the characters to see how accurate it was and I was very impressed by how small events had been covered to give this historical accuracy.

Regency women were treated as currency and people rarely married for love, instead being married into families for political or financial gain. Ultimately this is a story of double standards. Where the married women are condemned for having affairs, the men that they have affairs with are excused their behaviour. It is very hard to understand this with our 21st Century views as some of the behaviour I just couldn't understand - notably the marrying of cousins, which I just found strange.

If you are a fan of historical fiction then you will love this book.

Thanks to Netgalley and the publishers for the ARC in exchange for an honest review,

A fascinating story.

Harriet Bessborough is recalling her story regarding her dalliance with Lord Granville, and their affair throughout her life, and the grief and ordeals she also had to endure.

Her marriage to Lord B being unhappy, she began seeking affairs, but in a time where women are seen as property, she sought youth and vigor, and found herself in the arms of a younger man whom loved her fiercely. The story reflects highly on the double standards of life in the regency era, the cruelty of men in the era, and that love wasn't always a priority in marriage.

It was clear from the start that Harriet is a well educated woman, so her actions can be highly frustrating. I found that at times I was not rooting for her. Viewing this in a 21st Century worldview may have skewed this, but she was definitely making some terrible decisions.

I appreciated the shorter chapters and the writing style was eloquent and verbose. I really enjoyed it.

A very interesting account of the life of Harriet, sister of the Duchess of Devonshire. Although factionalism, it's packed with important historical figures of the time - Sheridan, Emma Hamilton, etc etc. Probably a bit long winded but enjoyed the account.

Thank you PanMacmillian and NetGalley for this ARC in return for an honest review.

Oh Harriet, what a life she led! The sister of the infamous Duchess (see the Keira Knightley film), Harriet has some interesting similarities as well as heartbreaks. I was rooting for her even though she frustrated me and awful lot. Her true love was a romance of both joy and suffering and I really felt for her. And yet what could she do? A woman of her station has remarkably little freedom which makes it all the more maddening. And the men in this book! Eugh.

I found the story of her life fascinating but I do wish it had been a bit more about her biography rather than just the romance - the parts towards the end and epilogue were really interesting. I had hoped for a more intimate telling but there was so much of just that: telling rather than showing. However it's written in a way that's supposed to be letters, so it makes sense but it's not a format I've always been fond of as it leaves me feeling detached to characters.

I appreciated the short chapter lengths and I'm left feeling fascinated about this woman, her family and society in Georgian/Regency England that is a bit more scandalous than what we are led to believe.

Unhappily married to an overbearing and insecure man, is it any wonder that Harriet, Lady Bessborough is in search of a passionate love affair, the like of which she has never known. Her reputation has narrowly survived a number of ill-advised dalliances before she becomes embroiled in a torrid love affair with Lord Granville, a man she truly cares for. Snatched rendezvous are all that they can hope for and the pages of the novel are filled with Harriet’s intensity of feeling - her all-consuming longing, severe angst and, at times when they are apart, abject melancholy. She lives for her next opportunity to be with Granville while doing her utmost to avoid besmirching her character and bringing scandal and ruin upon herself and her family.

In this work of historical fiction, Janice Hadlow has brought Lady Bessborough and her close circle to life. A circle which included her sister, Georgiana, Duchess of Devonshire. This allowed parts of the narrative to unfold at Chatsworth House and Hardwick Hall – settings which enhanced my enjoyment of the novel as they are places I’ve visited. Lady Bessborough’s support of the Whigs in opposition to Granville’s Tory leanings in the decades around the turn of the 19th century added an interesting political dimension to this romance novel as did the disquietude stemming from the French Revolution and the Napoleonic Wars.

Rules of the Heart is an accomplished historical romance novel which deals with the realities faced by upper class women of the Regency period who had affairs and reflects upon the double standards that society applied to men versus women in these circumstances. Although I never felt that I connected with the portrayal of Lady Bessborough or indeed any of the historical figures represented, I thought that the novel’s pacing was perfect and found the historical context fascinating.

Thank you to Mantle and NetGalley for sharing this eARC with me in exchange for an honest review.

If you have watched the Keira Knightley film "The Duchess" and enjoyed it, then this book will be for you. This is not focussed on the infamous Duchess of Devonshire but her sister Harriet. Historical fiction fans will like that this is based on the true story of the love affair between Lady Bessborough and Lord Granville,

I obviously knew all about the Duke and Duchess of Devonshire but nothing about her sister. Its nice to have a book that is based around the not so famous sister. Being interwoven slightly with the life of Georgiana there are incidents that I knew about but reading them from another lens was interesting. Georgiana is a peripheral character for parts of the book and not the main focus. The main focus of the book is the longstanding affair Harriet has with Lord Granville, it is interesting to see the parallels between her and her sister's famous affair with Mr Grey.

Narrated by Harriet, the book clearly provides clarity on her motivations and feelings, This is not a criticism of the writing, and also I am most certainly looking at this with a 21st century viewpoint, but my lord I find her frustrating. Its clear that Harriet is a clever woman but her whole life is dominated by a man that clearly has faults. There were times within the book that I just wanted to shake her to gain more self respect; I honestly didn't understand the attraction to Granville, He's described as handsome but in terms of character he didn't seem to bring much to the table.

Sometimes it felt like the prose was very dense and could have been broken up slightly more. However, what I did appreciate with Hadlow's writing is that I was engaged reading the book despite not liking the main characters and compared to other books I've read there isn't much in terms of 'things that happen'. The book spans 17 years and most of it is describing Harriet's life and feelings, which I remained engaged with the entire book. For a lesser writer I think that this could have become a tedious story but Hadlow manages to keep the pace of the narration moving forward that prevents tedium to set in.