W illiam Boyd, 70, is the author of 26 books, including Any Human Heart (2002) – adapted for television in 2010 with three actors playing the lead role of Logan Mountstuart – and Restless , the particular Costa novel of the year in 2006. His new book, The Romantic , is set in the 19th century and presents itself as a biographical fiction inspired by the personal papers of one Cashel Greville Ross, a Scots-born Irishman who fought at Waterloo, met Shelley, smuggled Greek antiquities and set out in search of the source of the Nile, among other adventures. Boyd, whom Sebastian Faulks has called “the finest storyteller of his generation”, grew up in Ghana and Nigeria and lives in London and the Dordogne, from where he spoke over Zoom.

Where did this novel begin?
My mid-20s were steeped in Romantic poetry because I spent eight years at Oxford not finishing a PhD on Shelley. I’ve always felt that nothing is wasted, and I was asking myself how I could recycle this material when I read The Life of Henry Brulard , the fantastically modern-feeling autobiography by [the 19th-century French writer] Stendhal, who I don’t think is much read in UK literary circles. He called himself a romantic because he kept falling in love – he felt it was a curse – and I decided that this store of knowledge I had about Passionate poets could gel along with writing about someone with that kind of temperament.

How does writing a “whole life” novel – this is your fourth – compare with writing your thrillers?
It’s more challenging. In a tightly structured spy novel like Restless , the plot machinery is part of the allure. Here, the narrative has to seem like it’s happening randomly, like life, yet it can’t flag: Cashel is 82 when he dies, and you can’t write a 5, 000-page novel with every month and every year. My other three whole-life novels are told in the first person, so nothing can happen plus it’s still interesting because of the voice. I was conscious that writing The particular Romantic within the third person meant that will things had to keep happening, even at the end of Cashel’s life. What I came to understand was that 19th-century lives were incredibly crowded; Anthony Trollope went to Australia twice and America six times.

What draws you to protagonists with different identities?
Maybe it’s my upbringing: I’m a Scot, but I was born within Africa, so I felt more at home in west Africa than in Edinburgh. If somebody asks where I’m from, I say: “How long have you got? ” Cashel gets called an Irish cunt, an English cunt and a Scottish cunt – that was highly deliberate, because, you know, what is he?