“Well, I do love coming back to London,” says Ioan Gruffudd, perhaps not sounding entirely convincing about a city he left to become a proper, fully-fledged movie star and live in California. Yes, he misses friends here, but after initial doubts, he now really enjoys living in LA – a sentiment not difficult to sympathise with on a wet, windswept morning in London. “But Wales was home, really,” he explains, and the place he still misses, despite forging a new life for himself Stateside along with his English fiancée, actress Alice Evans.

Ioan Gruffudd certainly sounds Welsh, with a lilting accent that comes as a bit of a surprise if you’ve got to know him as either Horatio Hornblower on TV or William Wilberforce in Amazing Grace, the recent movie about the campaign to abolish the slave trade. And let’s face it, his name – pronounced Yo-an Griffith – couldn’t be more Welsh, but Gruffudd never contemplated swapping it. “So what if it’s difficult to pronounce?” he reportedly told an interviewer early in his career. “We all learnt how to say Schwarzenegger.”

And we are learning how to say Ioan Gruffudd. When we meet he’s back in Blighty to work the red carpet at the London premiere of Amazing Grace, and also to do promotional work for Rise of the Silver Surfer, the latest in the Fantastic Four sci-fi franchise and thus a very different proposition. In this, the modest 33-year-old from Cardiff gets to play Reed Richards, an American “super-powered” hero who combats evil in the wicked forms of the aforementioned Silver Surfer and the wonderfully named Doctor Doom. Next up for Gruffudd, is the (voice of) animated hero Agent Crush in the film of that name, and a role alongside Sigourney Weaver and David Duchovny in The TV Set, which, as a portrait of life in the American entertainment industry, is rather closer to real life‚ as lived by Gruffudd today.

He’s not remotely starry, however, despite all the accoutrements of movie-star lifestyle: the stylist, the assistant, the publicist and, last but not least, those truly spectacular looks. He’s more than affable, cheerfully getting on with the business in hand – whether that’s being interviewed and jokingly explaining the absurdities of reacting to invisible, yet-to-be-executed special effects for the Fantastic Four films, or submitting to the grooming, styling and posing for the camera that, if you’re an actor with a square jaw and the looks of, well, a Greek god, or perhaps a Welsh god, goes with the territory.

“I don’t really think of myself as good-looking,” he demurs with an almost apologetic smile, not denying his good looks exactly, so much as seeking to maintain a healthy disregard for them. By the sound of it, friends and family help to keep his feet on the ground. His parents were both teachers, with a deeply held Christian faith. Today, having had a brush in his early twenties with the controversial London Church of Christ, Gruffudd, “wouldn’t describe myself as a deeply religious man”. But nonetheless, “playing someone like Wilberforce,” who was what we today would call a born-again Christian, “wasn’t such a leap of imagination.”

As a boy, Gruffudd was a keen musician, playing the oboe in a youth orchestra, before getting his first acting role in the Welsh-language TV soap Pobol y Cwm. Then came RADA and his first big break: as Poldark in the Nineties revival of the Cornish cozzie drama. Next came small roles as Oscar’s boyfriend, John Gray, in Wilde (“my first silver-screen kiss”), and as a young ship’s officer in Titanic. Then he got to do “all that swashbuckling stuff” as young Horatio Hornblower, the project that made his name in the UK and won an Emmy in the US. Back in London, Gruffudd lived a bachelor existence with his best friend Matthew Rhys – currently also enjoying success in the States in the TV show Brothers & Sisters, alongside Calista Flockhart and Rob Lowe – in what they jokingly called “the Welsh embassy”. Today, home is a little Spanish-style house in LA – a tiny piece of Wales amid the boulevards and palms of West Hollywood.

Fantastic Four: Rise of the Silver Surfer opens on June 15