Exclusive – Jojo Moyes on differences between The Last Letter from Your Lover book and film

"The reason for that was this has been kind of 10 years in the making," Moyes explains exclusively to RadioTimes.com. "So the original script was written before I even started writing scripts!"

"But I've been very much involved in the later stages," she adds. "I think, because I had such a good experience on Me Before You, working collaboratively with the director and the actors, I think most people who know me in film now know that I'm not going to be an obstructive presence – which I think some writers end up being, inadvertently.

"I understand the process, and I understand there's a certain diplomacy involved. And I also know my space on the food chain, which is basically lower than the catering truck! That's the truth for a writer in film.

"So yeah, it's actually been different [from Me Before You] but it's been really pleasurable. If I'm working with a collaborative director who wants me there to help tweak things at the last minute, then frankly, that's the dream. I love doing that."

So what changes were made to the novel? Read in for everything you need to know.

The Last Letter from Your Lover book to film differences

The film – which stars Felicity Jones and Shailene Woodley – is fairly loyal to the source material, telling two separate but connected love stories set decades apart.

As in the book, the film revolves around a journalist by the name of Ellie, who investigates a historical love affair between a socialite named Jennifer and a journalist named Anthony in the 1960s, after chancing upon a stash of mysterious love letters.

Whereas this historical love affair as it appears in the film is almost identical to the one in the book, Ellie's own love life has been given something of a substantial makeover for the big screen.

In Moyes' novel, Ellie has an affair with a married man named John, but this character is nowhere to be seen in the film – replaced instead by a brand new character called Rory, an affable (and single) archivist who works for the same publication as Ellie.

And the ending differs a great deal as well: in the film, Ellie tracks down the pair of lovers from the '60s storyline and persuades them to meet up, but no such reunion happens in the book.

Instead, the novel ends with Ellie learning her own lesson from the affair between Jennifer and Anthony and leaving her overbearing husband, who is also absent from the film (Ellie is instead recovering from a recent breakup in the film).

Explaining the rationale behind some of those changes, Moyes explains: "Well, the main thing is, when I originally wrote this book 13 years ago, there were no dating apps, the whole dating landscape has completely changed since then.

"I think it would have been very odd to have a story that was meant to represent the modern-day with no reference to that," she adds. "And I think a lot of that was [screenwriter] Nick Payne. He really substantially changed the modern-day plot, and I was totally on board with that, because I understood that it would feel wrong.

"And I think also, you know, writing about infidelity of any sort is a challenge. And I think with the Jennifer and Anthony story, it becomes very clear why you shouldn't judge this, why it's a necessary thing for both of them.

"Whereas I think that the character of Ellie I wrote originally in the book, who is part of a love triangle, her motives are slightly less clear, and her behaviour is probably less admirable.

"So I can see why two plot lines that involve infidelity might have felt like too much for the film, and I have no problem with what they changed for the modern-day plot-line.

Intriguingly, Moyes said that despite the relatively few changes made to the '60s storyline, that was the aspect of the film she was more involved in when it came to making tweaks to the script, "Just because I'm a perfectionist about things like language and the types of words that might have been used in the 1960s."

And most important to Moyes was that the spirit of the novel stayed the same – she says she was perfectly happy for substantive changes to be made so long as they did not interfere with the essence of her original work.

"I think, to be honest, Ellie remains the same character that she was in the book," she says. She's the same messy, slightly damaged person at the beginning of the book, so I didn't feel like we were losing who she was.

"And that's the thing that I've learned through being involved with other processes, you have to pick your battles. You are going to lose a bunch of stuff, because you only have 120 pages of a script and a 500 word novel, it's inevitable.

"So I think you have to work out right at the beginning: What is the essence of this? What's the tone of it? What's the spirit of it? What do I feel I have to retain of the characters?

"And I do feel, personally that we maintained who the characters were and the spirit of the book.

"I think, obviously, if they'd turned Anthony O'Hare into a kind of 1970s hippie, or a skateboarding dude from I don't know, it would be very different. But I've been lucky in that everybody's had a very similar vision."

But even if Moyes was more concerned with capturing the spirit of the novel than precise details, she was still happy to see some specific moments from the book make it to the final cut.

"I loved the fact that when Anthony and Jennifer first meet, she's reading Scoop, which obviously she gives him the nickname from, that's just a little, I think Augustine [Frizzel, director] calls them Easter Eggs or something, I just love the idea of those little things making it through.

"I think the thing that I love watching with Jennifer and Anthony is just the snappy language, there's a scene on the yacht where they're quite snippy with each other.

"There's a great phrase that Jilly Cooper, the novelist, uses, which is 'the helpless snappings of courtship'. And I feel like you get that they've managed to bring that from the book into the film quite a lot there. They make each other uncomfortable, and that shows before it becomes a kind of a huge love affair.

"It's that thing where you're thinking, why does this person unbalance me so much? And that's what still comes through."

The Last Letter From Your Lover is released in UK cinemas on Friday 6th August 2021. Looking for something to watch on telly this evening? We’ve got you covered. Check out our TV Guide or visit our dedicated Movies hub for the latest film news and recommendations.