Marcus tells me that the Scottish crowd have the best heckles.

“There was this fantastic woman last night, I would guess in her mid-fifties. I was doing some stuff on the moronic dentist that shot the lion – and as loud and bold as you like, in the broadest Glaswegian accent – she shouted,” Brigstocke then attempts in a gruff Scottish brogue: “‘JE SUIS CECIL!’”

He added, laughing: “It wasn’t aggressive or angry, it was absolutely in the moment. It was really, really funny.”

It’s the 42-year-old comedian’s 20th year at the Edinburgh Fringe, and he has shown no signs of slowing down in his middle age – taking two shows and an improv comedy to the world’s biggest arts festival.

Brigstocke said: “I always feel enormously privileged to take part in it. I get a buzz just being in the city. The moment you get off the train at Waverley, you’re like ‘BAM! This is Edinburgh.’ The incredible buildings, the castle... It feels magical, otherworldly – a bit like Hogwarts.”

With an air of nostalgia, Brigstock tells me about his favourite Fringe memory, when he stood across the carpark from Pleasance Courtyard with friend James and firing waterbombs at people using a massive slingshot, while another friend gave co-ordinates over the phone.

He added: “[Gilded Balloon founder] Karen Koren came out the front of the Gilded Balloon with a bunch of security guards. When we walked up, she said: ‘There are people on the roof throwing water bombs’ and we said innocently: ‘Aw really? That’s terrible.’”

He laughed: “This is summer camp for clowns.”

Brigstocke’s Assembly Hall show, Why the Long Face, is laden with anecdotes about his charmed, privileged life as a straight white man who gets inordinately angry about trivial things that don’t matter. He has also been working alongside Thom Tuck, Pippa Evans, Rachel Parris in The Beau Zeaux: An Improvised Comedy at the Pleasance Courtyard, which puts even the most seasoned comedian’s abilities to the test. But his Underbelly show Fully Committed is by far the most challenging; in his solo performance, he plays host Sam Peliczowski at one of New York’s top restaurants, and voices more than 50 different characters throughout the play.

He said: “It’s really fun to do and the audience is loving it. They come up to me outside afterwards, asking ‘how did you do it?!’

He added: “It’s been great! Though I feel punch-drunk after I leave the stage.”

That Brigstocke now gets his kicks just from performing comes as no surprise as a man that had battled with deep-rooted addiction in his youth.

Growing up in Guildford, Brigstocke developed an eating disorder when he was seven years old, and suffered from alcohol and drug problems in his early teens. At 17, hhe weighed 25 stone and was placed in rehab, shedding half his body weight in seven months. He has been tee-total for 25 years, but he still struggles with his compulsion to eat.

Brigstocke admitted: “I was losing control of everything. But it’s about humility, knowing when and how to ask for help rather than any willpower and self-discipline that I possess.

“I sometimes look at people drinking or smoking a spliff and think, ‘Oh, I wish I could,’ but it doesn’t last very long. Things are great as they are.”

He added: “I really owe my recovery to the wisdom of other people than I do to my own strength.”

It was Brigstocke’s late friend James who encouraged him to do stand-up after he failed to get into drama school five years later, getting him his first gig at a comedy competition in Holburn.

“He always told me ‘I don’t know why you’re trying to be an actor anyway. You’re funny!’” he said.

He added: “It’s a cliché but the first one I ever did, I was walking off stage and thought to myself “if I could do this for the rest of my life I’d be happy. What an amazing thing it is to be able to do, just make people laugh! Now I’m lucky enough to do both.”

A self-confessed ‘wobbly’ atheist, James’s death due to a heart condition in 2009 hit Marcus hard, making him ponder the big questions in life – which inspired him to write God Collar, his book on religion and the existence of a higher being.

  This led us to talk about Professor Richard Dawkins, the atheist movement’s enfant terrible, who is prone to Twitter arguments with trolls and controversial comments about Islam.

We agree that, while Dawkins is a brilliant scientist, is perhaps not the best communicator.

He admitted: “I think fundamentally that he’s right – but it’s not just the idea, you have to convey the idea.

“That’s what stand-up is, lots of ideas in my stand up are unpalatable or uncomfortable for people to listen to.

“The trick is how you convince people that what you had to say, even if they don’t agree with you, is worth listening to.”

He added: “He seems to have lost his ability to do that, or he’s just a miserable old git.”

Brigstocke has been the subject of criticism himself due to his liberal views on immigration. You don’t have to search far on the internet to find barbed comments from right-wing critics about the corduroy wearing, middle-class environmental campaigner’s public school education.

But his opponents only spur him on. His Mrs Brigstocke World Rape Tour gag in 2007, in which he talks about his neighbour saying that immigrants would come to the UK and rape his wife, is a long drawn-out satire which takes aim at the narrow-minded, xenophobic mindset held by many likeminded people in Britain  – but it doesn’t sit as comfortably with viewers who are taught to believe that rape jokes are the ultimate taboo.

Brigstocke argues that no subject should be off limits in comedy, that a performer can talk about something in a responsible way and make it ‘extremely funny.’

He said: “For me it’s about intent. It has to be well thought out. If the punchline of the joke is ‘and then she woke up’, I’d be like, ‘hang on a minute’ what do you mean? That’s rape, that’s disempowering – because if the victim of your joke is the victim of this act of violence, then I think you’re an irresponsible, lazy p****.”

One comedian he mentioned was Dapper Laughs, a controversial self-styled pick-up artist who came under fire for his infamous ‘gagging for a rape’ line at a live gig last year – resulting in his Channel 4 show being axed and shows being cancelled.

Brigstocke said: “I don’t care for the guy himself – he seems to be a very sad, poorly educated little boy. But the people who commissioned him and said: “Oh yeah, that would be good. That’ll be funny to have a sexually predatory guy talking about how he disrespects women – I just think it’s moronic.”

I point out that there are other comedians who make cruel, offensive jokes at the expense of others, but otherwise share compassionate, progressive views in the media. Russell Brand has been blasted for being sexist in his material, but is now something of a left-wing firebrand, with a radical best-selling book Revolution. In the past, Frankie Boyle has made ableist remarks about Down’s Syndrome and Katie Price’s son Harvey, but he now writes a political column for The Guardian. What does he think of that?

He paused for a moment, admitting: “I’ve said over the years far too much about Frankie, based on things I’ve seen that I’ve not liked. I made assumptions about what his intentions were. Some of those intentions were wrong. I think I misjudged him. I think he has a phenomenal mind.”

He added: “That’s not to say I’ve not liked everything that he’s produced, but the quality of writing that he’s creating now is breathtakingly brilliant.”

It becomes clear when speaking to him that he is very much of Boyle and Brand’s political ilk. Speaking passionately about the migrant situation in Calais, Brigstocke stated that capitalism was to blame for waging war in developing countries in the first place. He went on to criticise the British media for fuelling racist views and also criticised the government’s scaremongering tactics.

“There’s a furious anti-immigrant narrative in the country to terrify people. I believe ‘swarms’ is the word the Prime Minister used, which I think is disgusting –deliberately dehumanising them,” Brigstocke said.

He went on: “The Sun publish people like Katie Hopkins.. That’s the number one selling newspaper and that’s who they’re publishing.

“So few people who are critical of this situation have paused and tried to employ a bit of empathy to say, ‘huh, I wonder what it would take to leave everything I ever had behind and stand in the northern coast of a country, and do almost anything to get somewhere that I’ve been promised will be safe. What would it take for me to do that?’”

He added: “The fact is that left-wing and liberal people are better equipped to cope with new people and different cultures and all the rest of it, because that’s our nature.”

Brigstocke is undeniably intellectual – an eloquent public speaker who could easily counter any political argument posed to him with a good dose of humour. But as the interview came to an end, it was difficult to avoid asking about his year-long marital affair with Coronation Street actress Hayley Tamaddon in 2010, a high-profile scandal which resulted in him divorcing his wife of 12 years and the mother of his two children two years ago. Would he change anything, if given the chance?

Brigstocke replied firmly: “I’m very much of the view that isn’t anyone’s business. I don’t read that stuff about other people. Of course papers like the Mail on Sunday proffer an opinion on it, without any of the information as to what happened and why.”

He paused for a moment.

 “None of which is to say that I behaved in a way that I’m anything less than ashamed of,” he said.

He added: “­The most important thing to me is to be a good dad to my kids, and I’m trying day by day to do that as best I can.”

For a man whose comedy is often confessional, based on his own thoughts and harrowing life experiences, he still knows when it’s time to tell a journalist to shove it – but politely, of course.

Marcus Brigstocke is performing in Why the Long Face, Fully Committed and The Beau Zeaux. To buy tickets, visit the Edinburgh Fringe website here.