So, number 75, our first return visitor and a suitably epic chinwag. What was supposed to be a quick 20-minute phoner plugging Mark Thomas' award-winning tour show, Cuckooed, turned into a much heftier discussion about arms sales, corporate spying, conspiracy theories, politics, ISIS and, er, clitoral stroking. That's the way it goes with Thomas. You just don't get the same range with Peter Kay.

This chat happened back in mid-October, and I've since seen Cuckooed, a tremendously impressive, innovative, often moving piece of work, whose central character is an old activist colleague accused of spying for the enemy. Thomas isn't being pompous by calling it theatre, although to calm any potential unrest among the confused, he does also start the touring show with a bit of good old-fashioned stand-up.

Towards the end of this interview we meandered into the minefield of ISIS' assault on Kobane, an issue of such concern that Thomas has "found myself arguing against long held beliefs and positions." If you want to see him wrestle with that in person, he's staging a benefit at London's Bloomsbury Theatre on November 23rd to raise funds for Kurds displaced from Kobane, along with the likes of Josie Long, Tim Key and Jeremy Hardy. Do scroll down to Part Four for more.

Or ease yourself in gently with our underwear-based opening...

Part 1 - Pants

So what are you up to this morning?

I'm sorting the fucking accounts out. I'm now turning into a grumpy old fart, wandering round the house in my underpants and a t-shirt going 'what the bloody hell's happening?' The trouble is, because I've got a teenaged daughter, if it's the weekend it's like 'Dad, clothes!' because she has friends round, and the prospect of me walking round in my underpants...

The weird thing is my dad used to do this, I think I'm becoming more and more like my dad as I get older. He used to wander round the house in a free and easy way.

I definitely find myself shouting at the telly more. But I imagine you've always done that...

Yes, yes, a lot of shouting, at many inanimate objects, not just televisions. I actually opened the door to someone the other day in my underpants and a vest: 'What do you want?'

You must've done some doorstepping over the years - ever come across anyone in their pants?

Erm... I have stolen pants. Many years ago I stole [Liberal MP] Simon Hughes' pants from his washing line, and it was just the worst underwear you've ever seen in your life. I've forgotten what it was for.

Onto your new show then, which I noticed was in the theatre section of this year's Edinburgh Fringe guide, rather than with the stand-ups.

Well it's a funny old thing, I dunno if I'd describe myself as a stand-up anymore, because the last five shows, they've just been outside the remit of what a stand-up is. Certainly Bravo Figaro was a theatre show and so is Cuckooed, so where you actually place me in the world of stand-up anymore I don't know. I don't think you do.

But was this the first time you've actively been in the 'theatre' section?

No, Bravo Figaro was in the theatre bit, and that was a very conscious decision, because you want people to come to see the show with the right kind of expectation, if people come along and expect stand-up, it's like 'but why is he upset?'

Cuckooed you can describe it as many different things, because it involves people that I knew. It's a true story so we use footage of interviews of people I knew at the time who knew the guy who was spying for BAE Systems. So I interviewed them, we play the interviews in, I chat to them, they help tell the story.

But one bloke, down in New Milton, just did not have the wherewithal to actually be able to go 'what the fuck am I looking at?' He was obviously unhappy, he had this look on his face, and eventually he went 'I can't have this! I've paid for a night out, not a rant!' and he left. I thought that was hysterically funny - and sad as well actually, that he had so little cultural reference points, that he couldn't go 'oh right, so if it's not stand-up, then it's a rant' To see past that.

Then again, I've interviewed a lot of comics who've taken his point of view - that comedy should just be fun.

I have a lot of sympathy with them, the idea that people do work hard and do want a night out - but also that they want a night out that's just about nothing, not about their lives, new ideas, the world around them, that it's just a load of old shit, the background music for getting pissed? I'm not interested in that. I never have been, so for me, you've got to have some meaning and purpose to what you're doing up there.

Part 2 - Arms

This show is about the arms trade, and I've actually been reading your book about it, As Used on the Famous Nelson Mandela - but that came out in 2006. Did the revelations about your colleague spying on you happen quite recently?

The story first blew up over 10 years ago, that was when he was first accused. Friends of mine, we refused to believe that he was a spy, for a year we defended him, and that was quite a thing, we thought it was an act of betrayal to even look at any evidence. This guy wasn't just a casual mate. My mate Emily: Martin is the godfather to her son.

It's someone deeply entwined in our lives, who turns out to be passing info to BAE Systems. So the betrayal was a huge thing and it knocked all of us, really badly, the group of us who were really tight with him. You know, suddenly the guy we'd literally trusted with our lives is not the man we thought he was, you begin to unravel your own past, your own personal narrative, and go 'well, if our relationship wasn't true, what else wasn't true? Who am I? What was I doing? What was the truth to my story?'

It almost reminds you of the old Eastern Bloc, that whispering culture...

Well, I do think now corporate spying and state spying is out of control. I've met a lot of people over the last 10 years who've been involved with or been subject to spying on people for corporations. And it is really, really nuts. And there's no law, either, about it.

Consider this: if the police want to come and raid my house, and search my home, for evidence of a criminal activity, they have to get a warrant, they have to have a reason, they have to produce evidence, they have to talk to a judge. A spy has to do nothing to gain entrance to my home and the most personal inner secrets to my life.

You have a situation where climate change activists' court cases are being kicked out because of the undercover cops. And the fact that there's a whole load of evidence that wasn't revealed during the trial, wasn't disclosed properly; the police have perjured themselves in court, giving false names, false identities, while they're undercover. They've had relationships with women, they've had children with women while undercover, they spied on the Lawrence family. So you're looking at this whole world of spying.

There doesn't seem to be a huge ongoing media furore about this though, the way there was with phone hacking, MPs' expenses...

Well, there are court cases that are ongoing. There's a case about the police monitoring journalists, and there is the select committee, who are looking at the construction blacklist, where 3,200 workers were found to be on a blacklist, workers who were involved in trade union activity, leftists, health and safety - or activists.

I'm on the construction blacklist, as an activist, which is fucking nuts! That's another court case I'm involved in. You've got on that list men who haven't worked in a decade.

You're not on it because you used to work on building sites with your dad?

No, no, no! Listen, if there's a construction blacklist that had me on for just being shit, that'd be fair enough. If my dad found about it he'd probably have said 'that's probably best for everyone, love.'

But the construction blacklist is a real thing and the companies have admitted running it and they've offered everyone compensation - four grand. And everyone's up in arms about it, because some of these people haven't worked for 10 years, because of the blacklist. So what you've got to pay is 10 years' worth of full pay, and then compensation.

You mentioned various construction firms in the arms book too, for doing dodgy-looking foreign deals.

Indeed. The point about this is that the state is able to spy on people quite easily, and if you look at the RIPA act that was used on journalists... I know journalists aren't much-loved creatures, but they are fucking essential. When people talk about how useless journalists are and how corrupt and fucking shit they are, I say 'well, it was actually journalists who exposed the phone hacking' - how else do you think it happened?

If you've got the police using RIPA to find out a journalist's phone records, so that they can look up who they talked to and try to work out the source of the info about Plebgate - that is a little bit East Germany.

We had a chat a couple of years ago just after the Hillsborough revelations came out - I think that's when a lot of us realised that this shady stuff was really going on.

Somebody said to me the other day, I was talking to Radio 5 Live, they said to me 'are you a conspiracy theorist?' and I said well no, because there are conspiracies that do happen, and Hillsborough is one of them, the Lawrence Enquiry is another one - there was a cover up. Bloody Sunday was a cover up. These aren't theories, they're conspiracies.

It would have been interesting if Cuckooed had come out immediately after the Lawrence story broke, so you'd get that media momentum building about spying.

What's interesting, whenever we've done court actions, you always get more out in the disclosure than you do in the end result. BAE Systems' spying, right, people go 'isn't that a conspiracy theory?' No! They've admitted it in court. They've admitted to spying on Campaign Against The Arms Trade in court, and they've named the companies they hired. In fact, they've signed a legal undertaking saying sorry, and that they won't spy on Campaign Against The Arms Trade in the future. Britain's biggest arms manufacturer, that gets support from every prime minister, has had to say sorry to Guardian readers and Quakers.

Now that's not a conspiracy, that's not a theory, that's just true. In actual court documents.

Part 3 - Arts

I've come to the conclusion that your shows elicit a whole different type of laugh, for those particularly shocking revelations - a sort of amazed yelp.

You know, you've hit on something. I met a friend of mine who's a writer, who's just written a book on clitoral stroking. She told me she's attended the first international clitoral stroking seminar, and she said 'did you know there are 11 types of orgasm?' and I said I didn't - I feel grateful for just the ordinary one.

So maybe there are 11 types of laughter...

There's a book in that.

There probably is. I think you should do it.

Ah, Jimmy Carr's probably writing it as we speak.

I think he's written it while we've spoken, it's now finished and is nestling somewhere in the Caymans.

Probably right. So how did Cuckooed actually come about?

Well one of the lovely things that's happened is that I've worked with directors that I've been really fucking lucky to work with. After finishing Bravo Figaro I started working with a woman called Emma Callander, she's one of the directors at [Edinburgh's] Traverse Theatre. She works with Theatre Uncut, which is how I got to know her.

I caught one of the Theatre Uncut shows a couple of years ago - did you write a play for it?

I did! I completely loved it, and what was funny, I got a check for 100 quid the other day - 'this is for the sale of playscripts and performance of your show at the Young Vic' - I'm now a playwright at the Young Vic!

When we came up with the idea of the story about Martin I went to see the Traverse, I explained to them the show, so we worked with Emma, and she's really great.

You see a lot of 'directors' involved with stand-up shows these days - what do they bring to that crossover thing you're doing?

Well I think it's actually theatre. The two things I love are how you tell stories and engage people, and how you get other people's voices on the stage, and give them ownership of the story.

I'm always quite obsessed with that idea: how you break out of that idea of stand-up being a singular solitary activity, which is very Thatcherite in my view. The arts cuts go into the theatre world in the '70s and '80s, and you suddenly see stand-up rise, which is not coincidental. This solitary person, works very hard, they're like a self-employed businessman or woman, they go away, get the material, they have a vested interest in making it work, they'll appear on telly for promotional purposes, you don't have to pay them very much, and suddenly beer companies are finding that you can sell loads and loads on the back of it.

That's an interesting take on it...

For me it's always about how you break out past that, so I love the idea of other people being involved, other voices coming onto the stage. And this story is sort of a group story, it involved friends of mine who were betrayed alongside me, so this was a story that we could all tell.

It's about the narrative, that's the important thing with a theatre show, the story. If you chase every gag you will not construct a piece of work that sustains as a theatrical piece, that involves people, and engages them emotionally and intellectually. There's loads of stuff that we cut out, that we said 'this is really funny but it's not actually helping the story.'

Do you get any comeback from the subjects of these shows - threats of writs?

Well for libel, you have to tell an untruth. With this show we've been very careful, we don't give the [full] name of the person who's the spy, we don't say where he lives, we don't say the names of his family members, we don't show his face or play you his voice. We respect the privacy that he has in a way that he didn't for us. And we have to do that for a number of reasons, from ethical to theatrical.

I say this to people all the time: if someone wants to bring a court case against me for this, do it, just do it, because we will get disclosure. We will ask for every single document, and by law they have to give it.

I was watching All the President's Men last night, and thinking 'blimey, after this, then the Mark Thomas interview, I'll be totally paranoid.' But it's not paranoia is it, because it's all true.

That's a point, and also the fact is, the stuff that we look at is stuff that's in the public domain, and it's really important that you build it on stuff that's fact, which is why I love working with interviews from friends. I'll look forward to you seeing the show actually, because then you'll see the structure.

It's an interesting show, and it cost a fucking small fortune to put on, because you have to pay film-makers to film the interviews, editors, video designers. We have a really specific set on stage, technical people who work on it. The reason we published the playscript of Bravo Figaro and Cuckooed is because I had to write one. I had to write the script down, because the technicians needed to know when to press the buttons: 'Seriously, you can't expect us just to intuit it.'

So you've got a 'mark' to hit, like actors?

Yeah, absolutely.

Do you still do regular stand-up gigs too? Benefit shows, presumably?

I do loads of benefits. I did a Russell Brand thing for the fire brigade a couple of weeks ago, in front of a fire engine on [London's] South Bank. That evening I was doing a gala dinner to raise money for Palestinian medical aid, which was on this boat, with John Snow introducing it, and auctions. So I've gone from performing in front of a fire engine to a black tie event, John Snow goes up there and says 'let's start the contributions, will any table here give me £5000?' And people did!

Part 4: Action

In that arms book you're pretty scathing about New Labour - is it noticeably different between them and the current government?

There were differences - I don't think the Tories would've introduced the minimum wage, which, shit as it is, was better than a kick in the bollocks. And I don't think the Tories would have brought in tax credits, or Surestart. But I'm not a Labour supporter - I mean, I hate them...

I actually meant in terms of arms sales - you'd expect them to have different approaches.

Arms-wise, I think Tony Blair went above and beyond. You're looking at a man who cancelled the investigation of the serious fraud office into the allegations of bribery between Saudi Arabia and BAE systems, and again, I was part of the court case that challenged that. So he went above and beyond it, he overrode so many times. [Former foreign secretary Robin] Cook was an interesting fellah actually, because I think he had the right instincts.

Even the most ideological people end up compromising massively when they get into office.

A mate of mine was a Labour MP, and a real hardcore aid worker - she said when Robin Cook announced the ethical foreign policy he invited a group of them over to the foreign office, and they toasted a new era, where actually Britain's role as this colonial power - we still live in the hangover, the shadow of it - was finally swept away. She said there was such a feeling of optimism in the room it was incredible. Three months later everything had changed.

So how have our arms sales been under the Coalition?

Well, we supplied tear gas that was used in Hong Kong! We still supply equipment that gets out to Israel, there are court cases and challenges going on. Things do change, it's just that they don't change enough, and radically enough. I think the continual deal we've got with Saudi Arabia is outrageous, we still have the consequences of those deals as well. Saudi Arabia is a major funder of Sunni terrorists, including ISIS, and turkey is just fucking nuts.

I'm not pacifist, and in the book I say that I'm not pacifist - if the Western Saharans have the right to defend themselves then they clearly have a right to physically defend themselves, which means a gun. I'm against all sorts of things in the arms industry but I recognise that people have a right to defend themselves.

I had a row with the people at The Times who said 'shouldn't we be arming Syria?' This is about 18 months ago, they go 'what's the alternative, you and Gwyneth Paltrow and the UN?' and I'm like 'well, if the alternative to that is you and Murdoch flogging AK47s off the back of a truck, I'll go with me and Gwyneth...'

And actually, all of the people they would have been arming are now advancing on Kobane. And the Kurds, I've been following the Kurdish stuff for years, and the Kurdish community are saying 'we're facing stuff that's provided by America now.' ISIS have got American weapons.

That's always the way isn't it?

It's always the fucking way. And yet, for the first time in a very long time I've found myself arguing against long held beliefs and positions, and I actually think we should arm the Kurds to defend themselves. I actually think, if you don't in this particular instance, you could literally see that city under siege, and you could literally see the Turkish army waiting on the border. You're about to witness a massacre and I find that unconscionable. So it's kind of like, well, if you believe in people's right to defence, you have to [arm them].

Do you see that acting as a deterrent, or starting a war?

Well I think if the Kurds have got proper arms to defend themselves against ISIS attacks, which are artillery, then they'll stand a chance of surviving. If ISIS get into Kobane there will be a massacre without any doubt, and they're a third of the way in. If they take the whole thing it will just be a massacre.

Again, are we aware enough about this story?

Every morning Radio 4 is doing Ebola and Kobane - I wake up to the delightful fucking sounds of John Humphreys discussing these issues every morning. I think people do know a bit about Kobane, but not enough.

I'm finding this Ebola and IS stuff is making me more chilled-out, in a way. Everyday hassles suddenly seem totally inconsequential and not worth stressing about.

It's true, it's small beer by comparison. Like, my dog has a capacity to basically regard his bowel movement as a game of Wipe Out, so I have to chase him round, finding pools of stool. But I think, once you put it like that, it's all fine.

You don't do that in your pants too?

No, I did have trousers on while I was outside, I should stress that. God, how often do you finish an interview with 'No, I was wearing trousers outside'?

Cuckooed is touring the UK - visit www.markthomasinfo.co.uk for details. To buy tickets for the Kobane benefit show on November 23, go to www.thebloomsbury.com