That myth was formed, of course, in the crucible of Britpop. Twenty-odd years ago the comedian-turned-actor-turned- occasional-shouty-singer was a lively figure on a lively scene, carousing with fellow travellers and ravers like Damien Hirst and Blur's Alex James. There were drugs, there was booze, there were some more drugs, much of it consumed in the environs of The Groucho club in Soho.
The image of Allen-the-gadabout was reinforced by his daughter Lily. From the earliest days of her pop stardom she was forcefully honest about everything, including her chaotic childhood. It was scarred by her father leaving her mother, film producer Alison Owen, when Lily was four and her brother, Game of Thrones actor Alfie, was a toddler.
When I ask Allen if he has any guilt over that time, his answer comes immediately and firmly. "No. It was the worst thing I ever had to do; it was horrendous," he clarifies. " I was genuinely remorse – not remorseful, [and] guilt's the wrong word. It was the right thing to do, but I still had no excuse...yeah, I think it had a major affect on Lil."
Next month, Lily Allen publishes her tell-all autobiography, the tellingly titled My Thoughts Exactly. Even by the standards of an outspoken woman with a forceful social media presence, she doesn't spare the rod – nor the names of those who have let her down and/or been abusive in the past. Has her dad read a book that many expect to usher in the music industry's #metoo moment?
"You must be joking!", he splutters.
Why not?
"One, she's not asked me to read it. I know Alfie was very worried about it. And I said: 'Well, if you're that worried about it, you should ask Lily [if you can] read it, and see if you can have final say on what's in and what's out.'
"I have no idea where Lil will go with it. No idea." He says he's prepared to be painted in the worst light, "but, you know," he shrugs through a mouthful of lunchtime chicken Milanese, "we'll see."
Allen shrugs again.
"Listen, man. I'm not made of steel. But I have read stuff that Lil's said about me [previously] and I've thought: 'Really? Hang on a minute. That's not my memory, not quite.' But, you know, it's tricky, and it will be tricky… 'Cause like I say, me, in her eyes, abandoning the family, is a big thing."
When his daughter's memoir comes out, Allen will be front and centre in the nation's living room on the 13th series of Celebrity MasterChef which starts tonight. Whatever is revealed, Allen is adamant that he's nothing but proud of the 33-year-old mother of his two young grandchildren for standing up for herself, and for the causes she believes in – her privacy, refugees, Grenfell survivors. And for weathering the consequences.
He understands that certain sections of the media see his daughter, an opinionated celebrity with a brain, "as dangerous as having [Labour MP] Dennis Skinner up there, ranting [in Parliament]. It's actually probably more effective, because these are the times we live in. This small girl who sings pop songs is a threat to them. That's terrifying. But it's doubly terrifying for her," he says, sharply rapping the table twice.
Is it triply terrifying for him, as her dad?
"As a dad, of course as it is."
Nonetheless, does he worry for his daughter? She is, after all, currently promoting an album made in the wake of miscarriage, divorce and a horrific case of stalking.
Allen smiles and exhales. "She's such a tw**," he says affectionately (truly). "There is that. But there's a part of me, to a small degree, but certainly Lily to a much larger degree, [where] we're poultices. We bring out poison. And she is a poultice, and that poison will go towards her. And there's nothing I can do about that.
"I'd get worried if I thought MI6 were thinking she was so dangerous they'll have to bump her off!" he continues with a grin. "But I don't think we've ever come to that."
There is, too, another junior Allen coming down the entertainment pipe. Teddie Malleson-Allen is his 12-year-old daughter with Tamzin Malleson. He and the actress, 21 years his junior, with whom he starred in BBC medical drama Bodies (2004-6), live together near Stroud. I met Teddie in 2015, on the Yorkshire set of Swallows and Amazons, where she was playing one of the children and I was struck by this self-possessed and wholly un-bratty youngster.
Allen notes that she has his independent streak. But she also, it seems, has dad's and half-sister's punkish spirit. "Teds" is currently in Ireland, filming an adaptation of Jacqueline Wilson's Four Kids and It (itself an adaptation of E. Nesbitt's Five Children and It), with Russell Brand. Allen recounts how he and Teddie's mutual agent phoned to tell her she'd landed the part.
"And Tamzin did say to her: 'That's really good, darling. But you have to remember it's not a competition.' And Ted went: 'Yeah, it is actually, and I won!'"
Allen laughs his gravelly laugh. Does he think his youngest has learned at her father's knee, in ways good and bad? He nods.
"I think she Googles all the time. She says to me: 'So, have you been in prison, dad?'" he relates cheerfully, a reference to a 21-day sentence served in the mid-Eighties for criminal damage to a Covent Garden nightclub. "What can you do? But I think I've managed to present myself to her so that it won't come as any kind of surprise! I think she's prepped. I mean, her half-sister is Lily…"
The revelations in Lily's book will of course provide another lively chapter to the on-going Allen family saga. But Keith reiterates the concern comes not from the contents and more from what else it could unleash.
"It all depends on who she takes on. I'm thinking: 'Oh hell, you better weather this one, kid!'"
This article originally appeared on The Daily Telegraph.
