Striding through the foyer of a West End cinema on Monday night, Roy Chubby Brown, the rotund comedian infamous for his crude material, was confronted by a man in a Burberry mac and business two-piece brandishing a family-sized bucket of popcorn.

'Eat that, you fat northern bastard,' said the man, throwing the contents of his bucket down Brown's front. He then snapped back his head and emitted a thunderous roar of triumph.

'Are those your first set of teeth?' said Brown, brushing off bits of popcorn that were clinging to his expensive cardigan, slacks and white shoes. 'Cos they certainly won't be your last.'

At which the man roared even louder. He then turned to his friend, who slapped him enthusiastically on the back and shook his hand. Brown continued on his way, grinning boyishly.

All in a night's work for Roy Chubby Brown. The country's highest-paid live entertainer, the comic who works 300 days of the year but never appears on television, the spinner of filthy yarns who has grossed pounds 5.5 million from the sale of three home videos, was in London to promote a fourth. It was to be screened before a men-only audience hand-picked from the City. Tickets had been snapped up weeks earlier, someone probably made a market trading in them, and 500 excited men turned up to see him introduce his work in person.

'I had no idea all these business gents liked me,' Brown said in his soft Teesside brogue before the event. 'It's just an excuse for a piss-up, I'll bet. They'll all be loaded up, letting the beer talk. They'll be shouting abuse: 'Get off, yer fat bastard'. There's only one way to answer that. With a thump in the gob.'

Brown was almost clairvoyant in his assessment of the evening. As he walked into an auditorium packed with brokers and bankers, dealers and wheelers, he was greeted by a huge terrace chant of 'Sumo, sumo, sumo'.

'I have to say I'm flattered,' he said as he stood at the back of the theatre, signing 'Love and Bollocks, Chubby' on dozens of business cards that were shoved unceremoniously in his direction. 'I can't believe they know who I am.'

It does seem odd. Chubby Brown, bluer than Picasso's blue period, a purveyor of sexist goofery who makes Benny Hill look deft, being a cult hero among the biggest earners in the country. This, after all, is his own analysis of his appeal.

'It isn't avant-garde-read-between-the-lines-Monty-Python subtlety we're dealing with here,' he explained before the evening started. 'This is a fat cheeky-faced comic saying arse, tit, fuck and bastard and making it sound funny. This is toilet humour put across by a funny man. Full effin' stop.'

It was an approach that found favour with the country's cream. Take Rupert Armitage, a stock- broker, and a veteran of Chubby's stage show.

'It's just a laugh,' he said. 'We've come with a gang of us, have a few beers, we'll enjoy it. His one-liners are brilliant, though sometimes you laugh because you can't believe someone dares say that stuff.'

Matthew Tyler, a futures and options broker, had invited half a dozen clients along with him.

'Everyone wants to enjoy themselves,' he said. 'Get a bit raucous. It's not the sort of thing you want to do all the time, but it's fun for a one-off.'

As Brown wobbled his way down the steps to stand at the front of the cinema, raucous turned to ear-drum-threatening. He stood for a moment, blinking up at baying mob sitting in front of him.

'I was warned about this,' he said. At which someone yelled out a grossly impertinent suggestion from the second row. Everyone roared, and the chant of 'You Fat Bastard' was taken up by 500 throats.

'Excuse me, I must apologise for talking when you were,' said Brown to the heckler. 'No school tomorrer, eh? You're only shouting at me cos yer wife's uglier than Salman Rushdie and yer not gettin' it at home.'

With three perfectly timed put-downs, the Aunt Sally spun his audience round. They roared their appreciation, the heckler grinned in satisfaction.

'Well, I hope you enjoy my little fillum,' said Brown, scurrying to safety after a few unprintable stories. 'And if you don't, you can eff off.'

The video (in which Chubby is kidnapped by alien women from the future and put on trial for sexism) turned out to be scandalously bad: Viz without the irony, Jim Davidson after several years on a cholesterol-only diet. At first, the City boys amused themselves cheering pneumatic female characters and booing the men but, as it became clear this was not a production in line for an Oscar, the evening became a long procession to the gents. By the end, several over-imbibers had nodded blissfully off.

'To be honest,' said Matthew Tyler later, 'I found it a bit repetitive, tiresome, all that swearing. The odd put down was funny, but some of it was pretty revolting. Let's put it this way, I wouldn't have taken my mother along, or the wife.'

'I think it would be difficult to find anyone who would call themselves a Chubby Brown fan after that,' said Rupert Armitage. 'I suppose I should have guessed the tone from the message in the title: UFO.'

'It was,' said another man who didn't want to be named, post-rationalising the evening away, 'the kind of thing they probably enjoy up North.'

(Photograph omitted)