Eye Witness: Whatever happened to the great British liquid lunch?

Alcohol and the workplace no longer mix.

Four o'clock in the afternoon and a drunk is slumped on a chair outside McDonald's at Liverpool Street station, gulping down hot black coffee. He should catch a train, but his befuddled legs won't work properly. I know, because this sad case is me.

It's all the editor's fault. Go out for a few pints, he said. Three-quarters of bosses want to ban lunchtime boozing, according to a survey published last week, and one in three is thinking of introducing random testing for drink and drugs. But not mine. Oh no. He ordered me to take a liquid lunch in the name of duty, to see who else was doing it. Fair enough, I thought, better show willing.

The Brache is a new pub under the flight path at Luton, next door to the huge Vauxhall car plant and surrounded by office complexes. Something like 1,500 people work within walking distance, and the only other place to eat is a burger van. Surely I could find some drinking companions there.

Easyjet planes hauled themselves into the air overhead as men and women from Vauxhall head office wandered across to the pub, security passes tucked into suit pockets. The men preferred to stand by the bar in the traditional way – but their pint glasses were full of Diet Coke.

"There has been a real change in attitudes," said Neil Lucas, who had flown down from Edinburgh for a business meeting. "It is now socially acceptable to have an orange and lemonade, whereas in the past there was real peer pressure to have a beer."

All he had to do was get back on an aeroplane, so I managed to tempt Mr Lucas to a single pint of IPA. "I wouldn't do this if I was going back to the office today."

Habits have changed dramatically, said Gary Loader, the pub manager. "When I first started in this business you would see people getting absolutely smashed, then driving back to the office two or three hours later."

It took a while to find two ale drinkers. Mark Smith and Mike Murray, engineering consultants, had just finished an important presentation.

"Now we're celebrating with a half pint," said Mr Smith. "It wasn't planned and it isn't a regular thing," insisted Mr Murray, sounding guilty.

"We would never normally think of going into a pub," said Mr Smith. "And even if we do we normally drink mineral water. If a colleague came to the office with alcohol on his breath, that would be a subject for comment."

Drugs and alcohol are said to cost industry an estimated £2.8bn a year through absenteeism and reduced efficiency. Last week's survey, conducted by two charities with the magazine Personnel Today, found bosses yearning for strict measures despite the advice of experts.

"We need to get to a situation where organisations feel equipped to deal with people's problems in a sympathetic manner," said Mary-Ann McKibben of Alcohol Concern, "not through kneejerk reactions such as blanket testing or automatic sackings."

But it was clear from the Brache that many bosses had already terrified their workers into going teetotal at lunchtime. The final and extraordinary proof came from Mr Loader, who said the best-selling product at this public house surrounded by thirsty workers was ... water.

It was time to leave, and head for the only place I could be sure of finding dedicated lunchtime boozers: the City of London on a Friday. It may have been the quiet summer period with the dark clouds of recession gathering, but the Lamb in Leadenhall Market was crowded.

The tavern was established in 1780 and could not have been more different from the Brache, with its dark interior, iron staircase and converted gas lamps. The customers were all men, standing in groups. The only conspicuous woman was the Queen Mother, shown in a photograph pulling and drinking a pint.

The City is a paranoid place these days, and nobody wanted to give their full name or that of their employer. From the look of them, though, these were the middle managers out to play. A thin man with slightly stooped shoulders disguised by a beautifully tailored blue pinstripe suit picked on a baguette like a crow after carrion. The menu at the Lamb was simple: beef, sausage or pork in bread. The food was definitely not the point. The beer was splendid.

Outside in the dim light shed by the market's glass roof, two men in their fifties nursed pints and discussed cricket. One had snowy hair and wore a red tie; the other had a haircut and diffident manner that made him look like an over-age schoolboy.

Snowy agreed with random testing. "If only!" He would have preferred the young ones in the office not to drink at lunchtime but couldn't stop them. "You make a mistake in our game and it costs a fortune."

His third pint was slipping down nicely. "This is different. It's Friday. Nothing's going on. All our clients are out doing the same, I should think."

Would they be going back to the office? "Just to pick up my case and show my face," said the Schoolboy.

I watched, drank and listened for three hours. A camera crew filmed it all from across the street as though preserving a disappearing tribe. Out in the real world the culture may be changing, but the City still has its own rules.

Snowy and the Schoolboy left after four pints each, in the lull before the early evening crowd. They walked in that expansive way men have when full of drink: arms swinging, jackets open, cheeks blowing. The Schoolboy strolled into Broadgate Circus, but Snowy had met a friend. They shook hands and went to another pub.

I had to follow them, you understand. My job was to watch, keep up pint for pint, and see how fit for work that would leave me. Snowy is back at his desk but I feel utterly incapacitated. So if you don't mind, I'll just go and find a bench for a little lie-down.