Insults? Abuse? All part of the service: Martin Hennessey joins the waiters from hell to serve unsuspecting diners at an exclusive hotel

Basil Fawlty would have been proud of me. The scene was a sumptuous banquet at The Belfry, in Wishaw, north Warwickshire, one of Britain's most exclusive country retreats. There was a battalion of serving staff, divine food, and me, Britain's most obnoxious waiter.

Dressed sharply in bow-tie and crisply pressed black trousers, I might have been expected to be on hand to cater to every whim of the corporate diners. In fact, I was causing havoc.

A bald diner on table 'L' caught my eye. He asked politely whether he might possibly have some extra croutons with his soup.

I flashed him a look of contempt. 'Certainly, Sir. If I show Sir where the kitchen is, perhaps he would rustle up a few for everyone else, too?'

As his face changed hue - from a lobster bisque through to the purple of a fig - his fellow diners tittered.

And I was not the only waiter behaving badly. Over on table K, the diners looked shocked, as one of my colleagues calmly leant across and lit his cigarette from the candle in the centre of their table. Another was chatting up an attractive woman in a black, backless dress while her boyfriend looked on in fury.

This was the most important night of the year for the US-owned Beneficial Bank, based in Croydon. It was the annual dinner for its 170 sales representatives. Unbeknown to the guests, however, things were not intended to go smoothly.

I and five other members of the 30-strong restaurant staff were not all that we seemed. I had joined - for that evening only - a subversive corporate entertainment outfit called Spanner in the Works.

For three hours we worked alongside genuine members of the hotel staff. But while they diligently served their guests, we did all we could to upset them. The bosses of the Beneficial Bank, and the hotel management, were in on the joke. The bank had paid Spanner in the Works pounds 700 to upset their guests. They were quite happy to have their employees abused, ignored, insulted and berated.

The question was, how much abuse could diners take before they realised it was all a huge joke? The answer turned out to be a great deal.

My colleagues Steve Wattison, his brother Neil, Mark Walmsley, Myfannwy Squirrel (alias Becky Wadlow - the team's only female member) and Nigel Barden went to great lengths to enrage them.

While Steve lounged in a corner, taking long swigs from a bottle of white wine, Neil flicked his cigarette ash into a bowl of crisps. When an elegant lady in evening dress rebuked him, he replied, unfazed: Madame, if you knew where these snacks came from, you would flick ash on them.'

While Myfannwy asked: 'Ladies and gentlemen, would you be so good as to keep your grubby fingers off the clean cutlery', Nigel picked up one hapless woman's place marker and said: 'Is that really Madame's surname?'

'Yes,' she replied sweetly.

'I am sorry,' he said. 'Has Madame considered remarrying?'

It seemed that nothing would make the guests complain, or lose their tempers. Not even Nigel's sneezing into someone's main course. And when Myfannwy forked up the largest potato from a woman's plate and stuffed it into her mouth, all she got was a shocked stare. When Neil answered a request for more gravy by dumping a giant catering pack of HP Sauce on the table, he received only pitying looks.

It was not until the sixth member of our troop, a bogus maintenance man, entered the room that the guests finally realised that they had been set up.

Under the pretext of checking the ceiling for 'loose asbestos', Charlie was causing havoc. Guests gasped as he spun a huge step-ladder inches above their heads. 'Won't be a mo,' he chirped.

One by one, the diners collapsed into laughter as they finally got the joke.

The evening was considered a great success. Beneficial Bank saw Spanner in the Works' substantial fee as money well spent. And the members of the troop were relieved that the night had not ended in blows.

'Last month,' said Steve Wattison, 'I was pinned to the ground and nearly throttled by a man. He had a fork ready to stab into my eye. Thank God his wife pulled him off in time.'

Spanner does a roaring trade. Since the idea occurred to Mark Walmsley and the Wattison brothers in 1988, when they were asked to come up with a novel entertainment for a friend's office bash, they have received an average of one or two bookings a week. They never advertise, relying on word of mouth to get their act known, and have tormented guests at corporate bashes thrown by A&M Records, Antler Luggage, British Airways, Bass, Bang & Olufsen, Braun, Canon, and Coca-Cola.

Mark Walmsley, a musician with the Birmingham Philharmonic by day and a Spanner waiter by night, says: 'It's a great laugh and pays well. Basically this is the closest thing we can do to earning money without it seeming like work.'

The man who booked Spanner for the Beneficial Bank, the firm's public affairs manager, Gordon Lockyear, is in no doubt why they are so popular.

'From the moment people cottoned on to the wind-up, the team spirit among our guests was incredible. Everyone was laughing at themselves, and the way they had reacted to the situation. The only disappointment is that a company can only ever hire Spanner once. After that people know the joke.' But for one occasion, the idea worked.

'We wanted something that would get people going. Break the ice a bit.'

Basil Fawlty to a T.