When Martin Freeman was shooting The Hobbit: The Desolation of Smaug in New Zealand, his assistant Seamus decorated his Winnebago with record sleeves from the Sixties and Seventies. And when he wasn’t being Bilbo Baggins, Freeman would pop along to Slow Boat Records in Wellington, happy in the knowledge that he’d hired a good sound system to keep him company in his rented house. ‘When I made Breaking and Entering in 2006 with Anthony Minghella, I took a portable plastic record player and a box of records on set with me,’ he says. ‘It made me feel at home, but the quality was pretty awful. If you’re going to win the argument about vinyl, you’ve got to have good sound.’

Freeman is happiest when talking about music. Any music. We quickly move on from Morrissey’s Autobiography – ‘I like the fact that he’s alive, but I’ve never been a fanatic’– to his changing relationship with vinyl: ‘I’ve bought fewer records recently. If you put a record on, then you have to engage with it, and it’s harder to justify that time with two young children. You can’t expect your kids to engage with music the way you do. I’ve tried: they know all the lyrics to the Small Faces’ “Lazy Sunday”.’

Music, he says, is his touchstone. If he’s not listening to it or reading about it, he’s gazing at record sleeves and wondering where he can buy the jacket. Just as he’s vague about his musical taste, classing it only as ‘diverse’, so Freeman is reluctant to refer to himself as a mod (perhaps because he fears it’s too mainstream, post-Bradley Wiggins). Yet he has that specific sartorial air about him: the button-down collars, the desert boots, the hair cut.

Anyway, the point is that music was his first love. ‘Music pre-dates everything else for me. I used to draw pictures of myself and a couple of friends at St Patrick’s Catholic Primary School in Farnborough as punks.

I really thought we’d be in a band. Clearly we weren’t going to be at six… the thing is that I don’t have an ironic or trendy relationship with music. It’s my most basic artistic outlet. Having said that, I truly love acting. If I wasn’t an actor I’d be deeply frustrated.’ In this sense at least, Freeman isn’t really a musician manqué. He needs to act, but he doesn’t need to play music. Now a youthful 42, he seems to have been around for ever – although it’s only a decade since we saw him in Love Actually and The Office. When he talks about acting, it’s as an old pro: he has learnt, he says, to shut his eyes and listen to music between takes. He was tempted to throw himself totally into his latest role, once again as Bilbo Baggins, in The Hobbit: The Desolation of Smaug, but experience told him to pace himself.

‘You learn different things at different points in your working life,’ Freeman laughs. ‘If you come out of the traps at full speed, you’ll be done in a month. Slow and steady wins the race. Equally, you learn how to talk to different directors. It’s never ever been enough for me to say, “Well, if the director likes it…” I have to please myself first. Pete [Jackson, director] is the boss, but we learnt to share our ideas.’

The Desolation of Smaug is obviously set to be a global blockbuster. Yet Freeman insists that it is Sherlock that has provoked the biggest reaction of all his projects. ‘It’s phenomenal. I’d watch it if I wasn’t in it. Jealously. I don’t think it was a massive surprise that Ben [Cumberbatch] and I wanted to do more of this exceptionally successful show.’ Suddenly he grins like the Cheshire cat. ‘My missus [the actress Amanda Abbington] is in the new series. She was over the moon to be asked.’

Freeman is just about to head off to Canada, where he will be spending most of his time until April next year shooting the 10-part FX reboot of the Coen brothers’ Fargo. He talks about his decent Minnesota accent and of the prospect of missing his family. It’s a tough balancing act, but he couldn’t be happier with his lot. ‘I sometimes ask myself what the 19-year-old me would have made of my working life. In so many ways, it’s gone so much better than I could’ve dreamed.’ Freeman chuckles to himself, before adding, ‘But in another way, I probably thought I would’ve won an Oscar by the age of 30. After all, look at what The Beatles did at 26! But then acting isn’t very rock’n’roll. I’ve got some time before I burn out.’