I'M ten minutes into an interview with Stewart Lee, and it's not going well.

Intermittent mobile reception means we've already had three beginnings, which is bad enough. But thanks to a couple of opening questions which seem to have failed some kind of critical sniff test, the prospect of a meaningful conversation is looking unlikely even if the phone signal doesn't continue to break up.

"Have you ever seen me do anything?" Lee asks at the start of the fourth call-back, in a tone I'd describe as civil but travelling towards accusatory at well over the speed limit.

I have, and I tell him so. I tell him I've interviewed him before too. I tell him when and where. I tell him he gave me a lift to Clapham tube station in his Mini afterwards. I even tell him what we talked about.

"Oh. Right," he says.

I try an ice breaker: does he still have the Mini?

"I had to get rid of it when I had kids," he replies.

Emboldened, I try a second, my never-known-to-fail David Bowie story - another stop-start telephone interview, equally plagued by call-backs. It meets with dead silence. But I'm going to take it as approval.

Lee is driving right now as it happens. Or being driven: to Guildford, where he'll take to the stage for Day 36 of a tour which began with a three-and-a-half week sell-out run at London's Leicester Square Theatre. It arrives in Edinburgh next week for the first of five Scottish dates, one of which takes in the Glasgow Comedy Festival. The 46-year-old returns to Scotland in August for a slot at the Edinburgh Fringe and he'll end the year as he began it, with another Leicester Square residency.

The year-long show is called A Room With A Stew and it's essentially a way for Lee to work through the material which will form the fourth series of Stewart Lee's Comedy Vehicle, his award-winning BBC Two show.

"Normally when I write a tour show it's got a title that means something - a beginning, a middle and an end - and some kind of storyline and ideas going through it over two hours," he explains when the line finally settles down. "The ones that have stupid titles like this one are just little mixtures of half-hour blocks of material. I'll have six or seven on the go and hopefully end up with six that will make the TV series."

After a year of honing and finessing the routines, Lee will film the six-parter in December for transmission in a year's time. As usual, each episode will feature him performing in front of a live audience and musing on a particular topic, usually of the weighty variety: religion, politics, global finance, crisps.

Intercutting the stand-up, and helping give the Comedy Vehicle its very particular flavour, are segments in which unscripted questions about comedy are put to Lee. In series one and two, the interrogator was Armando Ianucci, also the show's executive producer. In series three it was Chris Morris, who doubles as a script consultant. It's a comedic dream team which first assembled in 1991 when the trio worked together on BBC Radio Four's current affairs satire On The Hour.

"He's very hands-off," Lee says of Morris. "He doesn't necessarily put a lot in but what's good about him is that he'll stop you making a mistake. He's a very clever man and he knows about all sorts of things in politics and history, and he's able to help me clarify things. But I don't use any writers, which I know is increasingly rare, and I sometimes feel that some of my peers dislike me for that. I do get an awkward feeling that I'm somehow letting the side down by not joining the Use An Underpaid Writer party."

Lee's method of creating his TV series is personal and exacting, then, but it's that rigour which has seen it twice nominated for a BAFTA (it won in 2012) and handed the 2011 British Comedy Award for Best Comedy Entertainment Programme. Lee won Best Male Television Comic in the same year.

"Rob Brydon said he didn't understand why I did all these tours working stuff out," he says. "He just writes an hour and learns it and then goes straight into the theatre with it. That's because he's not really a stand-up. Stand-up is more of an organic process. An imagined dialogue with the audience. And by the time I come to do it on the telly I want to have explored all the different things. I want to know where I can improvise, where the gaps are, and where I can change things.

"For other comics it's about full-spectrum dominance, being on panel shows and having one-liners and being a good chat show guest and having a good seven minutes you can do on Live At The Apollo. But I really think about these subsequent finished pieces, you know? And they don't always chop up well into one-liners and routines."

More than that, he wants each episode to have an emotional arc both for his audience and for him - or the stage version of him anyway. "I can't write that," he says, "I have to feel it on the stage."

What we're not going to see in the live show, however, is much discussion of the coming election. Working on material which won't be televised for a year means sticking to generic subjects rather than specific ones.

"If you try to say anything about politics, everything could change," he admits. "To be honest, when I first started thinking about this fourth series I assumed Scotland would be independent. Now I've got a good half-hour on Ukip, but I'm painfully aware that is almost completely irrelevant to Scottish politics."

That doesn't stop him having political opinions, though, and after a little coaxing he's happy to share them.

"The bad people have got all the money and all the resources and control of everything," he says simply. "If only someone else were leading the Labour Party that had more charisma, that would be good for everyone."

And who would that person be?

"The woman who's running the SNP, Nicola whatsit. She should take over the Labour Party. I was thinking the other day that there's nobody in British politics that you could imagine negotiating with Putin, for example, is there? Apart from her. She'd do alright with him. Everyone else just sort of folds. It's terrible."

Lee does currently have a segment on attitudes to Islam in his show but even that's a fluid subject, particularly after the recent events in Paris and Copenhagen and the arrival in the UK this month of the Pegida movement.

"Obviously that [Islamophobia] became something people were very nervous about in January because of the Charlie Hebdo murders, and the way people were responding to the routine changed. So I kind of hope they get the series out pretty quickly after filming it so that things are perceived in the way they are meant."

Talking of fluid subjects, Lee says he'll also be talking about urine in A Room With A Stew.

I assume I've misheard. "Urine?" I query.

"Yeah, urine," he replies, like it's the most natural thing in the world. In his, I guess, it is.

IN an era which often seems to prize novelty and newness over age and experience, Stewart Lee is bucking the trend by proving more popular as a stand-up now than he's ever been. In part it's because after 25 years he has a cross-generational appeal. In part, it's because he can talk winningly for 30 minutes about urine. In part, it's because he's almost a curio - he likens himself to one of those ailing, veteran American bluesmen who toured the UK in the 1960s and found an entirely new audience to impress and inspire. "I think that's what it's like for young people," he says. "[I'm] a sort of animated corpse dangling in front of them."

But there is another reason for his popularity: the paucity of talent elsewhere.

"A lot of the people who are coming now have seen comedians off the telly so their standards are lower and they're excited by me," he says. "Previously I was playing to people who'd seen Daniel Kitson or Simon Munnery or whoever. They were less easy to impress because they were used to seeing better stuff."

Nor is that his only broadside against the battalions of young wannabes who stream across BBC Three panel games and stand-up shows like so much comedic cannon fodder. Today, there is no "idealogical backbone" to most stand-up, he thinks. Instead, it's all about celebrity.

"I don't think I'd want to be a comedian today if I saw it on the telly. I wouldn't think it was a thing for weirdos and drop-outs, I'd think it was a thing for squares who wanted to be famous."

And if these comedians are disposable, so are the DVDs they produce. "All these ones by the people off the telly, they get bought for Christmas and watched once," says Lee. "There's a load of jokes and then they're gone. It's like eating crisps. And then they go to the charity shop. You don't see mine in charity shops because people really like them and they hang on to them."

A confession: I've made the mistake here of using the phrase "revenue stream" in connection with comedy DVDs, and receive a lecture in return which makes it clear that "revenue trickle" would be more appropriate. As if to prove the point, Lee reveals that one of the reasons he left his previous management company, comedy behemoth Avalon, was that they couldn't even give away the rights to film his live shows. Nobody was interested. He now has a deal, but even so the margins are tight.

It's not the money, then, that makes Lee produce DVDs. Instead it's what they symbolise: a finished piece of work that can't be returned to except by the person who has bought it and who (Lee hopes) will pass it around their friends like some precious bootleg. As for Lee, putting work "to bed" means he has to continually move on, continually create.

"Also," he adds, "I like having a merchandise table with about 20 hours of stand-up mapped out on it like a display of Russian tanks rolling across some plain towards the citadels of other comedians' feeble back catalogues. So it's like a 'F*** Off' display of all the stuff I've done. Which is quite a lot."

Mind you, not everyone views Stewart Lee as a comedy purist to be praised for his devotion to edgy, authored TV series, creative but commercially unviable DVDs and intensive gigging. His sort-of-namesake Lee Mack once dubbed him "a cultural bully from the Oxbridge Mafia who wants to appear morally superior but couldn't cut the mustard on a panel game".

True? Well, he did go to Oxford. Born in Shropshire and educated as a scholarship boy at the private Solihill School in the West Midlands (other notable alumni: Richard Hammond and the drummer from Napalm Death), Lee studied English at St Edmund Hall. At Oxford he met and performed with Richard Herring, later his comedy partner in TV programmes like This Morning With Richard Not Judy, and as well as his years of left-leaning, politically-themed stand-up he has written a novel (The Perfect Fool) and even a musical: the satirical Christianity-baiting Jerry Springer The Opera, which caused a furore when it was staged a decade ago but won four Olivier awards. And no, he doesn't do panel games.

But just to prove that even a dust-up between stand-ups is something you can make humour from, Lee turned the tables somewhat by using the quotation in a self-referentially superior Mack-baiting skit for the last series of the Comedy Vehicle.

He also put the line on his website along with dozens of others in a section called Online Critiques. "If this is supposed to be a 'Comedy Vehicle', someone had better call the RAC to get it started," is one of the few comments that could safely be read out on Points Of View. A second critic writes that Lee seems to think live comedy "should just be kept to smoky art student union clubs and that any comedian that plays in arenas is destroying the so-called 'artistic integrity' of stand-up". A third just wants to hit him with "a s***-covered cricket bat". Most of the rest are shorter and employ the C-word. And no, it isn't comedian.

Still, Lee clearly laps this stuff up and so does the character he assumes on stage, a curmudgeonly middle-aged smart arse who doesn't know about apps or smartphones and doesn't care to know either.

"I increasingly feel like one of those High Court judges in the 1960s who said 'What is a Beatle?', or the lawyer who said 'Would you let your wife and servants read this?' about DH Lawrence," he admits. "I increasingly encounter aspects of popular culture and I can't really believe it's actually happening. But I find that really funny."

Not depressing?

"No, I find it mainly funny ... Having come into comedy when it was the new rock 'n' roll and everyone was supposed to look like pop stars, it's great to be allowed to become old. I think an old man being mad and angry is funnier than a young person doing it."

And with that a rhythmic barking noise comes down the line. It might be just a final burst of static, of course - but I think it's the sound of Stewart Lee laughing, long and loud and hard.

Stewart Lee is at the Festival Theatre, Edinburgh (March 15), Dundee Rep (March 16), Eden Court Theatre, Inverness (March 17), Perth Concert Hall (March 18) and the Clyde Auditorium, Glasgow (March 19), www.stewartlee.co.uk

For more information about the full Glasgow International Comedy Festival programme, go to www.glasgowcomedyfestival.com