Nick Frost admits he has an odd relationship with dancing. ''I really like doing it,'' the comic British actor says. ''But I don't like anyone watching me doing it. Being a big man who can dance well, there's a look that thin people who perhaps can't dance as well as you give you. It's the same look you might give a young child who has beaten a terrible disease and who has gone on to complete a half marathon. It's 'aw'. It's like pity.''
Frost, whose star has risen with the ''Cornetto'' film trilogy - Shaun of the Dead, Hot Fuzz and The World's End - with Simon Pegg and director Edgar Wright, has turned his enthusiasm for dancing into the underdog comedy Cuban Fury. He plays a shy, overweight office worker - and former junior salsa champion - who returns to the dance floor to win the affections of his new boss (Rashida Jones).
Trailer: Cuban Fury
Beneath Bruce Garrett's shabby, overweight exterior, the passionate beating heart of a salsa king lays dormant. Only one woman can reignite his Latin fire.
But with competition from a sleazy office colleague (Chris O'Dowd), he needs help from his alcoholic former trainer (Ian McShane).
The movie, directed by James Griffiths (Royal Wedding, Episodes) was Frost's idea. ''I think secretly I wanted to do a big dance film,'' he says. ''The genre films that I've done before with Edgar and Simon were very different to this in terms of putting the training in and doing a film, which is just a happy, good-hearted comedy with dancing in it.''
It's also a movie with echoes of Strictly Ballroom. ''It was a wonderful Baz Luhrmann film and a touchstone for me,'' Frost says. ''I said to a lot of people during the build-up to the making of this 'this is what it needs to be: the comedy needs to be funny, the drama needs to be dramatic and the dancing needs to be beautiful and passionate'. If you're going to do a film about salsa dancing you need a big, wonderful finale, as well as the bits building up to it.''
Frost knew the movie had to be more than just the one gag - big guy looks funny dancing. ''If you're just relying on that, you have a problem,'' he says. ''I don't think you can rely on any one thing as a comedic device. It has to come from lots of things. And the thing about the dancing is, apart from a dance fight with Chris that is blatantly funny, his [character's] dancing is not funny. It's the unfunniest thing in the film. That's the thing that he finds again.''
Frost had to go through the salsa equivalent of bootcamp to play the role.
''It was so hard,'' he says. ''It was about six hours a day, going up to seven hours a day the nearer we got to the shoot, five days a week, sometimes six, for seven months. That's all I did. A car came and got me at 6am every day and I was a dancer for seven months.''
Learning to be a polished salsa dancer proved to be an emotionally taxing experience, which led to Frost walking out on dance instructor and choreographer Richard Marcel one day.
''It gets too much some days when you're in the seventh hour and it's Thursday and you're knackered and you're four months in. There comes a point when his language sounds like Mandarin. I'd literally look at him and say 'I have no idea what you just said to me. What do you want me to do?' He manhandled me. He got a bit cross and moved me. I'm from that odd ilk where it's like 'Don't f---ing touch me'. It's kind of funny because I ran out into the toilets at Pineapple Dance Studios really sobbing. I came out and there were, like, five really attractive shirtless male ballet dancers looking at me going 'Are you all right?' 'Yeah, I'm fine, I'm fine.' I went back in and Richard tried to give me a hug. I said 'Just f---ing leave me, Rich, will you?' I got my bag and I ran out.''
While everyone admires Daniel Day-Lewis when he spends months preparing to play a character, Frost says people ask him ''why did you bother'' when it came to his intensive dance training. ''I can see that as an argument,'' he admits. ''There's no BAFTA nomination for most effort. Which is a shame really.''
It's kind of funny because I ran out into the toilets at Pineapple Dance Studios really sobbing
Cuban Fury is now showing.