1) Sense and Sensibility - Jane Austen:

This may come as a shock, but when it comes to Austen literary heroes, I actually have more love for Willoughby than Darcy. I know he's a rotter and breaks Marianne's heart (not to mention that other unfortunate business, ahem), but he's just so dashing. And romantic. And darn sexy! I think it's my devotion to him that makes his final letter to Marianne all the more poignant. We all know what it feels like to love someone who no longer loves you back, and when Willoughby returns Marianne's letters and lock of hair and informs her that he's marrying snotty old Miss Grey, my heart still breaks every single time.

Isabelle Broom by Connie Heale

Isabelle Broom by Connie Heale

2) Pride and Prejudice - Jane Austen:

There are lots of letters in this classic tale, but the most pivotal for me has always been the one Elizabeth Bennett receives while in the company of Darcy, informing her of her sister Lydia's elopement with Mr Wickham. As well as being an utterly juicy plot nugget, I think it's also the moment that Elizabeth realises she loves Darcy after all. Nothing quite like the thought of losing someone to make you want them like mad - and we're all still going through the same nonsense nowadays!

3) Atonement - Ian McEwan:

This book had such a profound effect on me when I first read it. The plot isn't overcomplicated, but I think if anything that adds to the novel's impact. Robbie's letter to Cecilia, which he writes during a moment of lust-fuelled madness, is never meant to be seen by anyone other than him. But of course it gets into the wrong hands, and the results are nothing short of devastating. It's a perfect illustration of just how powerful the written word can be, and how much depends on interpretation.

4) Harry Potter And The Philosopher's Stone - JK Rowling:

No matter how many times I read and re-read the Harry Potter books (there have been a lot, I assure you), I still get a thrill when I reach the part where Harry finally gets his magical mitts on that letter from Hogwarts. No matter how old you are when you read these books for the first time, there's a small part of you that believes JK Rowling's world could, just might, be real, and it's this desire to believe in magic that makes the books so tremendously enjoyable. Harry's letter from Hogwarts marks the beginning of both his and our journey into a new world. Simply magical!

5) 84, Charing Cross Road - Helen Hanff:

This beautiful story is told through the letters exchanged between British bookshop employee Frank Doel and US author Helen Hanff, and was later made into an equally beautiful film starring Anthony Hopkins and Anne Bancroft. What starts as professional correspondence about rare books develops over time into a genuine friendship, with the two writing to each other for 20 years about all sorts of things. The fact that it's a true story just makes it all the more touching, and I've always loved the fact that it was the pair's passion for books that bonded them so inextricably.

6) Into The Wild - Jon Krakauer:

This true story charting the life of Christopher McCandless, a young man from Virginia, America, who took off "into the wild" and tragically died from starvation aged just 24, broke my heart the first time I read it. Here was a man who was struggling to find his place in a world that he saw as oppressive, a man who had ideals that many would call foolish, but that he truly believed in, and he'd ended up dying a lonely death away from his loved ones. It was while Chris McCandless was in Alaska that he fell ill, and each day he would head out from his makeshift home inside an abandoned bus to forage for berries. As his health deteriorated, the young man wrote a letter and fixed it to the bus while he was out. It includes the words, "I am injured, near death, and too weak to hike out of here. I am all alone. This is no joke. In the name of God, please remain to save me." I have never been able to forget those words.

7) We Need To Talk About Kevin - Lionel Shriver:

This is a book that always springs to mind whenever anyone mentions the subject of epistolary novels, but while I was actually reading it for the first time, I remember forgetting that I was reading a series of letters. Lionel Shriver has managed to make the first-person narrative just as thrilling as any crime novel you'd pick up, but it's this personal angle that makes the book so unforgettable. There's a real sense of dread from the very opening page, and when you reach <that> chapter, the pay-off does not disappoint. It's a chiller in every sense of the word - and a huge achievement.

8) PS I Love You - Cecelia Ahern

It still makes my jaw hit the desk whenever I'm reminded that this book was Cecelia Ahern's debut, and just glancing at the cover gets me teary. The letters that Gerry leaves behind for Holly after he dies are the epitome of heartbreaking romance, but at the same time they manage not to be corny. It's 12 years old now this book, and it still feels so fresh and original. I absolutely love it, and I think it demonstrates perfectly just how powerful the written word can be. Gerry loved Holly enough to know exactly what she'd need and when she'd need it - he's one of the ultimate romantic heroes of all time. Perhaps it's no great surprise, then, that my romantic hero ended up being Irish…

9) A Place Called Winter - Patrick Gale

This was one of my favourite books of last year, and it was one of those miraculous novels that I opened with absolutely no expectation and ended up utterly entranced. Set in turn-of-the-century Edwardian England and the colonised Canadian prairies, it tells the story of Harry Cane, who is forced to leave behind his family and his home and move abroad after a scandal. Harry has a younger brother, Jack, who he adores, and when he receives a letter from his estranged sibling informing him that due to the scandal surrounding Harry's departure from England, he can no longer have any contact with him. For Harry, who has already lost his parents, wife, child and a huge chunk of his dignity, it's almost too much to bear. It was this part of the book, and this letter, that really made me fall for the character and his plight.

10) The Unlikely Pilgrimage Of Harold Fry - Rachel Joyce

I adore this charming and hugely uplifting tale of retired Harold Fry, who gets a letter one day informing him that a friend has cancer, only to end up embarking on a journey across the country to visit her. He only means to send a note back in reply, but when he gets to the first postbox, he has second thoughts and walks on to the next, and so on. I don't want to give away too many details or spoilers, but suffice to say that it is this initial letter that changes Harold's life and acts as the catalyst he's been waiting for, similarly to the letter my character Holly receives at the start of My Map Of You. Sometimes what you need to make a change is someone giving you permission to, and this is exactly what happens in both these cases.