A Hitler moustache is a disconcerting thing, and there's one on the face of Richard Herring.
In every other respect this stocky 41-year-old writer and comedian looks almost anonymous in a Hammersmith coffee shop in his gym-friendly T-shirt, sweatshirt-material top, and shoulder-length brown hair. But there, on his upper lip, is a couple of centimetres-square of facial hair that has more cultural and social baggage than a combined world tour of the Chinese State Opera, the Iranian parliament, and the North Korean missile display team.
It shouldn't be this way. It's just facial hair. Charlie Chaplin had one. Freddie Starr wore a fake one. And even swastikas have been co-opted by punk, and then worn by royals as a joke. And yet a real, bushy toothbrush 'tache still pushes buttons deep in the psyche. If you saw Herring recently on Have I Got News For You, then maybe you'll know what I mean.
Herring is famous for going to difficult places with his comedy, and I don't just mean the Glasgow Empire. His in-yer-facial topiary is from his show Hitler Moustache, in which he tries to reclaim the growth from its place in the iconography of terror; the piece had a sell-out run in Edinburgh last year, and led to a spat in print with a critic who accused him of being part of a "new offensiveness" in comedy. Yet since his early years in a double act with Stewart Lee, Herring has become well known for envelope-pushing shows such as Talking Cock, inspired by The Vagina Monologues, for his no-holds-barred improvised and unedited weekly podcasts with Andrew Collins, and for writing Al Murray's TV breakthrough series as the ironically mega-patriotic Pub Landlord, Time Gentlemen Please. Now he's doing an eight-week run at London's Leicester Square Theatre with As It Occurs to Me, a show that he writes anew every week and then podcasts, and he's about to publish How Not to Grow Up, a frank memoir that he hopes his parents won't read.
I wonder whether there is an element of self-indulgence in his relentless experimentation with taboos in front of paying audiences. "But you wouldn't go and see Macbeth or Hamlet," he counters in his hugely voluble, high-speed, largely unstoppable way, "and say, 'this is taking me to places I'd rather not go'. I don't understand why comedy has this thing where you're not allowed to discuss serious issues or upset people or shock people.
"What's interesting about Hitler Moustache [he has just finished its latest run] is that I've had very few walk-outs compared to other shows that I've done, and the people who have complained have all been cross about completely different things. If you're a sensible person with a world view then you understand that the joke earlier on about the Holocaust that you laughed at would offend someone else. In a show where I make glib jokes about the Holocaust, to get upset about paedophilia or a girl that's been kidnapped [he does a joke about Madeleine McCann] I think is to miss the bigger picture... I had a UKIP supporter and a big thuggish skinhead and a Catholic woman all in the same week calling me a liberal as an insult, and I thought, I'm probably doing something right if all those people are annoyed with me for different reasons."
The son of a head teacher, Herring grew up in Somerset, "obsessed with sex and comedy from the age of three. I had a very happy upbringing; I love funny people and love to make them laugh. When everyone was listening to pop music I was listening to Monty Python records." He went to Oxford, where he met Stewart Lee, and they began performing as part of university revues in Edinburgh, where he had "a really horrible time. Keith Allen and all the stand-ups just vented their feelings at us for being Oxbridge. Ironically, all but one of us were comprehensive kids who got good A-level results, so we were just the kind of people they should have been applauding."
He and Lee began writing for the BBC, contributing to Chris Morris and Armando Iannucci's On the Hour, where Steve Coogan's Alan Partridge was born, and then their own radio and TV vehicles, Fist of Fun, Lee and Herring, and This Morning With Richard Not Judy. But Herring's experience of the commissioning process was frustrating. He tells of the moment at a party when Coogan introduced him to Jane Root, one-time controller of BBC2, "and she just turned her back on me without saying anything, and I thought 'we [he and Lee] are probably not going to get another series'." And Time Gentlemen Please was picked up by Sky after the BBC had overlooked it. All this has helped push him to his pioneering use of the internet.
"We've been doing the Collings and Herrin podcast for more than two years," he says (his and Andrew Collins's name are deliberately misspelt). "The internet is a very exciting way of doing material that's uncensored, and doesn't have to go through TV committees, and people aren't telling you what you can and can't do." It also avoids the Jonathan Ross/Russell Brand scenario: "Audiences choose to download them, so it's not as though it's going into an old lady's house and she's getting upset by it."
Herring is hugely prolific. He writes 365 blogs a year, 52 podcasts a year, 45 minutes of new material every week for As It Occurs to Me (so that's about six hours-worth this year) and several hours of other new material. So it's no surprise that he had more than one book in him.
"I had all these ideas for books, like a blogs book, and a dieting book, and a giving-up-drinking book, but my editor said, 'do it all in one book'. It's based on the year I turned 40. In the first six months I'm living this debauched and disgraceful life, and then I meet my girlfriend and calm down a bit. I don't really want my parents to read it but I suppose they will – I'm pretty honest about all the stuff I got up to."
I wonder if there are any subjects he won't go near. "I don't like people doing jokes about disabled people for no good reason, but I can still understand why they do them." He mentions the very recent furore about Frankie Boyle doing several minutes of stand-up about people with Down's syndrome. "You can understand why he's doing it, and it's part of his persona, so it's weird to get upset with him in a way, but I'd prefer people didn't do those kind of lazy jokes about disability."
And he says he really doesn't want to offend anyone, even though he agrees that the power and humour of some of his routines depend on the need for some people to be offended – otherwise, "it wouldn't be funny". When people are offended, "it kind of does upset me, but usually I've got an idea if I've gone too far." He has, he says, to be sure that what he's doing is defensible, stressing that the intent is important. And, ultimately, he says, he's the victim. "I have to walk around with this thing on my face for seven months of the year." With that, he's off to run at the gym. In a Hitler moustache. Well, they call it body-fascism.
'As It Occurs to Me', Leicester Square Theatre, London W1 (Leicestersquaretheatre.com) every Monday, tonight to 21 June; the show's podcast and the Collings and Herrin podcasts are available free on iTunes. 'How Not to Grow Up' is published by Ebury Press