Bernard Cribbins pauses, sips his tea and struggles to think of something left to do. "I've never been in a circus but I think I'm too old and slow for that now.
And I've never done a Western. I don't think I'm good enough to ride a horse but I could drive the chuckwagon and be Clint Eastwood's dad or something. Or brother even, because we're about the same age. I'd be the grizzled old thing at the front, cooking beans. I'm very good at the after-bean thing with the Blazing Saddles scene, hee, hee!"
The truth is that, at 80, after nearly seven decades treading the boards, there's almost nothing he hasn't done. It will be second time round for him in the Tardis this Christmas when he steps aboard as the Doctor's companion – Donna's grandfather, Wilf – for David Tennant's final two episodes. "When we got into the Tardis back in April or May, I said to him, 'The last time I was in the Tardis was in 1966.' There was a slight pause, and he said: 'I wasn't even born then.' I felt very, very old. 'Help me up! Help me up!' I said."
Even a stint at number one in the pop charts these past two weeks – as the voice of the Wombles in Peter Kay's Animated All Star Band song for Children in Need – is his third taste of Top-10 fame. "For about three weeks in the 1960s I was nearly a pop star," he chuckles.
His singles, "recorded by George Martin, before the Beatles got a hold of him", might not have hit the top spot but they have staying power: "Right Said Fred" (No 10) inspired the 1990s pop trio and Noël Coward choose "Hole in the Ground" (No 9) as his ultimate Desert Island Discs pick, something that tickles Cribbins every time he thinks about it. "When Roy Plomley asked why, [Coward] said, 'I could translate it into French as I walked up and down the beach.' Isn't that great? I never met the gentleman, but I would have loved to and say, 'It was me! I did Hole in the Ground!' He would have patted me on the head and said, 'Of course you did, dear!' Wonderful."
"Wonderful" is something Cribbins says frequently. Not in any raging, luvvie way but because, you get the impression, the years have generally treated him pretty well. Leaving aside that early Tardis outing, in Daleks – Invasion Earth 2150AD, he's probably best known as the station master Mr Perks in The Railway Children, a role that gained him a Bafta nomination.
Playing the part was a career highlight. He recalls staying in Yorkshire with his wife, Gill, and fishing for trout every night after he was through for the day. "I only found out at the end of the fortnight that I was poaching because I didn't have a ticket."
Although Cribbins has played many other roles – most memorably, for him, on the stage in Guys and Dolls at the National Theatre – it is for his work in children's television that he is probably best loved. Never mind the Tardis; just listening to his smooth, deep tones are enough to transport most people back to their childhood.
As well as narrating the Wombles, his was the voice of Jackanory for millions of children: Cribbins made the most appearances on the show with 111. He has also recorded the complete Winnie the Pooh, including the new David Benedictus book just out, and Howard Blake's The Snowman. Forget National Treasure; he is the National Granddad. This despite having no grandchildren of his own. His wife had an early miscarriage and they never had any children.
We meet just after he has picked up a special award at the Children's Baftas for his contribution to entertaining pre-teens. And educating them. He recounts a trip he made in a black cab: "The driver, a black guy, an East Ender, asked me what I was doing. I told him I was going to do a little bit of filming for Roald Dahl because I used to do Jackanory, and he said, 'Yeah, Jackanory. I remember that. It made me want to learn to read.'
"It's absolutely beautiful that: the cherry on the top for me. Shakespeare couldn't have put it better. It. Made. Me. Want. To. Learn. To. Read. You know; sitting there in the East End. I think it's fabulous. That's what kids' TV is all about. It entertains; it stimulates; it educates, and maybe, in some cases, it unlocks a bit of potential in a child, which they've all got, haven't they? That sounds rather pompous, but it's what I feel."
These days Cribbins reckons children would be hard pushed to get inspired to pick up a book by what they see on the box.
He is particularly upset at how people tell stories on TV. "Nowadays, it seems you can't just have one talking head, you have to have flashing lights and CGI and everything has to go 'click, click, click' the whole time. I think they've lost faith in a child's attention span."
Even the CBeebies' bedtime hour story, which like Jackanory is read by someone famous, has been messed with. "Now they have you finishing a sentence or a chapter and then coming in through a door or something. They're trying to move it along like a movie but I'm not sure that's necessary. I mean, mum and dad don't walk around the bedroom and then suddenly leap out of a wardrobe and continue with the next paragraph," he harrumphs.
It was never his master plan to major in children's work. "I've no idea why it happened. As an actor, you're a labourer and you get engaged to do certain jobs. I was just asked to do some kids' stuff."
The son of a plumber's mate and cotton weaver, he was born and brought up in Oldham, Lancashire. He says he fell into acting: "I was 14. I was offered a job and it was easier than looking for work, so I'm here by accident. It was just as well because I can't do anything else."
The only break from acting was while serving with the paratroopers during his National Service. He saw action in Palestine in 1947 and 1948 but "was desperate to get back to the theatre".
Despite all the film and TV roles – his movie credits include Peter Sellers and Alfred Hitchcock numbers, plus a couple of Carry Ons and She, with Ursula Andress, while his TV work memorably includes being mistaken for a hotel inspector by John Cleese in Fawlty Towers – theatre remains his favourite. "It always has been because it's what I know best. You're in charge. The only thing they can do is turn the lights out and even then you can go on shouting." Another chuckle.
He peppers his stories liberally with names of theatre greats, past and present, with whom he has worked: Lionel Blair, Edward Woodwood, Imelda Staunton, Peter Cushing, Elaine Paige, Patricia Routledge, Gillian Lynne ... the list is long.
But he claims to have broken his last theatrical leg. "It takes an awful lot of energy and I think I'm a bit too tired for it now. I was asked to do a panto, but I said, sadly, no."
Now that he has – slightly – more time on his hands, he can indulge another love: fishing. He has just finished making eight hour-long programmes on angling, Catching the Impossible, with the wildlife film-maker Hugh Miles.
Nothing, apparently, beats casting into the surf to fish for bass. He is, nevertheless, pleased with a surprise catch just before we speak: some motley feathers he spotted in a skip. He's only too happy to pose with them for our photographer, briefly unleashing some of his inner luvvie in the faces he pulls, before taking them home to turn into trout flies.
As for whether, despite turning 81 later this month, Cribbins might have one last Doctor Who innings left in him with the 11th Doctor, Matt Smith, well, he reckons stranger things have happened: "Perhaps he'll say, 'I wonder what happened to that old fart, Wilfred, and he'll ring me up and say, this is the Doctor.' And I'll say, 'Who?' and we'll do all the jokes."
'The End of Time: Part One', is on Christmas Day at 6pm on BBC1; Bernard Cribbins also appears in 'Buzzcocks – the Doctor Who Special' this Wednesday at 10pm on BBC2
An actor's life
1928: Born in Derker, Oldham, Lancashire
1942: Took a job with Oldham Rep aged 14 and stayed for eight years.
1956: Made West End debut playing the two Dromios in A Comedy of Errors.
1962: Had three novelty hit records: "Hole in the Ground", "Right Said Fred" and "Gossip Calypso".
1963: Appeared in the first of three Carry On films.
1965: Co-starred with Peter Cushing in the film of H Rider Haggard's novel She, with Ursula Andress.
1966: Played comic policeman hero Tom Campbell in Daleks – Invasion Earth 2150AD beside Peter Cushing's Doctor Who. Presented Jackanory, the first of 111 appearances.
1970: Nominated for a Bafta for Mr Perks the porter in The Railway Children.
1973: First narrated The Wombles.
1975: Played spoon salesman Hutchinson in Fawlty Towers "The Hotel Inspectors".
1976: Became the voice of Buzby, the talking cartoon bird used by Post Office Telecommunications, and later BT.
1983: Recorded Howard Blake's The Snowman.
2003: Guest starred as Wally Bannister in Coronation Street; also in Last of the Summer Wine.
2007: Appeared as Wilfred Mott in the Doctor Who Christmas special, "Voyage of the Damned".
2008: Reappeared as Wilf, Donna's grandfather, in Doctor Who, pictured left.
2009: Won a Special Award at the Children's Baftas.