He's used to being in the spotlight, but for once in his life it wasn't Harrison Ford getting all the attention during his recent trip to Britain, but the blonde actress with him.

It was supposed to be a promotional trip to publicise his latest movie, but the actor's visit quickly turned into a game of "spot Calista Flockhart".

But mention the 'C' word during the interview and we were warned by his PRs that Ford would get up and walk out - which of course only added to the mystique already surrounding this elusive star.

But if he was being secretive about his latest love, it quickly became pretty obvious to everyone just why the stunning 37-year old actress and 60-year old Hollywood veteran have become an item.

Quite simply, Ford is in great shape and looks amazing for his age. His skin is remarkably unlined and his 6ft 1ins physique enviably fit and lithe, yet the star says he doesn't do much to keep trim.

"I used to work out but I got bored, so now I play an hour or two of tennis and I'm careful what I eat. I'm lucky genetically I guess," he says with a shrug.

And, unlike many of his Hollywood contemporaries, Ford seems genuinely comfortable with the ageing process. In his latest film K-19 The Widowmaker, he has to age drastically on screen, but says he found the whole prospect interesting rather than unnerving.

"It didn't bother me at all. It was just interesting to have the opportunity to play beyond my actual age - given my actual age is already considerable," he says with a wry smile.

The movie, out this week, is based on a true story and stars Ford as a Russian nuclear submarine captain who is confronted with a potential nuclear catastrophe when his sub's reactor goes into meltdown.

Although it's described as an action movie Ford's character is not a typical action hero, which he explains, attracted him to the role.

"There are no good guys versus bad guys in this story, no politics," he says. "It was a rare and unusual character for me. It was a character that wasn't defined with the usual devices to gain sympathy. He is a hard man to know. But my goal was to have audiences come to an appreciation of those who served on K-19. As in any group, there were all kinds of people on board. But when threatened with a terrible situation they came together with heroic and selfless behaviour."

As part of their research for the roles, Ford and his co-star Liam Neeson travelled to Moscow, to meet the survivors of the real K-19 submarine, an experience Ford says will stay with him forever.

"It was very informing to me and what was important was to know emotionally how they felt during that period of time," he says. "It was the defining moment of their lives and I felt it was an honour to tell their story and it gave me a great sense of responsibility to get it right."

Filming of the movie proved to be gruelling for the two stars who, not only had to endure a harsh Russian winter, but also spent weeks cooped up in an exact replica of the K-19 submarine.

Despite his age, Ford prefers to do his own stunts.

"The fact that I do the scenes myself means you get an emotional component that's missing if the stunt guy is doing them," he explains.

He'll get plenty of opportunity to do that again when the fourth instalment of Indiana Jones begins shooting next year.