It's an all-white dining room, the St John Hotel: white walls, white tablecloths, and there in the corner is a dark, somewhat hairy patch that, on closer inspection, turns out to be Keith Allen. He has his laptop out and only slightly reluctantly, it seems, turns away from his screen and towards me.
It was his idea to come to here because "I know Margot and Fergus and I wanted to see what it's like". Fergus being Fergus Henderson, the chef who pioneered nose-to-tail eating at St John Bar & Restaurant, in Smithfield, almost two decades ago, and Margot, his wife. The St John Hotel, just off Leicester Square in central London, is a sister hotel and restaurant, their latest venture, opening earlier this year. "It was actually Margot I met first. At the Groucho Club. In the halcyon days."
The Groucho and Keith Allen go together like, well like, media luvvie land and coke-snorting celebs. Which isn't so very far from being a description of how he spent the 90s. He had an early career in stand up, and The Comic Strip Presents, and an arresting role as the dead lodger in Shallow Grave, but he was also well known for hanging out with Damien Hirst and Blur bassist Alex James, getting drunk, snorting coke, and co-writing a couple of World Cup anthems, one with James, Vindaloo, the other, World in Motion, with New Order.
For someone who spent his teens in borstal, and a couple of weeks in the 1980s in Pentonville prison for smashing up a bar in Soho, Allen is now an abstemious sort of hellraiser. "I don't like the taste of alcohol," he says. "I hardly ever drink. I don't see the point of it. Unless it's to get pissed." Which he doesn't really do these days, he says, though he orders a glass of rosé, but more I think for politeness sake. He makes an exception for cider which he makes on his Cotswolds smallholding.
Although it turns out the C-word, the Cotswolds, is the first of a number of contentious topics. These days he grows chard and raises pigs and lives the good life with his partner, the actress Tamzin Malleson, and their five-year-old daughter, Teddie. So, what do you make of the Cotswolds, I ask.
"It's not the Cotswolds," he says. "Well, it's the outer edge. Minchinhampton. It's nothing like you're implying."
Actually, I haven't implied anything at this point. The sensitivity is that in the last decade the Cotswolds has become a sort of rural Groucho Club, organic kale and homemade chutneys being the new drugs of choice.
He moved out of London seven years ago and has embraced country life. "We buy very little food these days. Just some meat. There's so much fruit at the moment, it's fucking ridiculous. We make our own pesto. Our own chutney and jams. Our own sloe gin."
It's probably not quite the image most people have of you, is it?
"I don't know where people get this image from. How would people know what I eat?"
I suppose it's the reputation you've had for sex, drugs and rock and roll.
"The reason why William Burroughs continued taking heroin all his life, and Keith Richards, is that they only bought the best. So there are ways of taking drugs, and there are ways of taking drugs."
So, it's a bit like food? You need to know the provenance?
"Yes. You just have to watch it. You don't have to eat the shit that's available."
The character he plays in his newest television series, The Body Farm, has a not un-Keith Allen-ish backstory. Though it's not in the script. The show is a spin-off of forensic detective drama Waking the Dead, and he likes the role he says because his character, DI Hale, is so "normal".
The part was originally written for a much younger person. "But I spoke to the director and I said there was this intake to the police in the early 80s, when there were three million unemployed. Some people became policemen because there were no other jobs. A lot of them were ex-punks. And I know this from experience. And I sold them this idea, that he was one of these people. He still had his punk record collection and his values. But you never see them. They're never espoused."
We order, both choosing razor clams for our starter, turbot with roast tomatoes as main course. And then Fergus Henderson appears and comes over to our table. "Big man!" says Allen and they chat. Henderson mentions that he's doing a couple of food festivals. Then there follows a convivial chat which Allen strangely and abruptly insists is "off the record". Although what he also says is: "never you mind", "none of your business", and "keep your nose out". We return to the apparently safer topic of food.
"I refuse to eat processed shit. I'm lucky because I can avoid it. Not everyone can. But you can take certain steps. I just think it's wrong, what people have done to food. Like Alex James, he's now producing cheese that is bread sized, and has tomato ketchup in it. I just think, 'What are you doing?'"
The razor clams, on the other hand, are delicious, and Allen tells me how to collect them. He's just back from a holiday on the Pembrokeshire coast, not far from where he grew up in Swansea. One of his most vivid food memories is of going to get his gran's shopping, his reward being a raw sausage "which I then sucked the meat out of".
His father, a submariner, was, he says, a harsh disciplinarian. "He said the other day that he was sorry he never encouraged us to draw," he says. "But nobody did in 1951. It's only because he comes to my house and sees reams of terrible drawings by Teddie."
Teddie is Allen's youngest child. Although he has had a number of high profile jobs, such as the Sheriff of Nottingham in the BBC's Robin Hood, one of his other claims to fame is being Lily Allen's dad. It's another controversial topic: "I'm not here to discuss my children."
It's a matter of record that she's pregnant, so I ask him if becoming a grandfather feels like a milestone.
"Not at all. There are 40-year-old grandfathers these days." He split up from Alison Owen, mother of Lily and her brother Alfie, when the children were small, and later married Nira Park, ending that marriage when he met Malleson on the set of TV hospital drama Bodies. But at 58, he says he's better equipped for fatherhood this time around. (In 2005, he told this paper that "no one knows how many children I have – there's a rumour it's seven" but this time the topic provokes a terse "no comment".)
We have pudding – he has chocolate terrine with malted ice cream, I have strawberry trifle – though he says he's not a pudding man. Just like he's not a pub man ("don't like them"). Or a drinking man. What he is, he says, is a performing man. I ask him about something he said in a previous interview: actors just want to be loved.
"Maybe, but mine is not much of an ego-driven showing off thing. Although I'm sure there's a part of me which wants to be adored. I love all aspects of performance. It's equally rewarding to be in Groucho's, off your tits, making people laugh. Or putting on a night every month in Stroud – I write songs and play in a house band. That's enough for me."
He finishes his pudding. "Food is just fuel," he tells me, not altogether convincingly for someone whose idea it was to come to one of London's finest restaurants. But then Allen logic is nothing if not a) impenetrable and b) illogical. I say goodbye to him, and leave him to go back to his organic curly kale and his home-reared pork.
