Outside the pub on a wet south London traffic intersection, the prevailing mood is downbeat. But inside, although it's only 11.15am on a Tuesday, the atmosphere is lively. Lively and very old. New Labour, in malevolent collusion with the big brewers, long ago priced the UK's senior citizens out of modern life. If you wondered where they went, I can tell you. They're in Tooting Wetherspoons, drinking heavily.

They're not drunks - the drunks, distinguishable by their cans of super-strength cider and distinctive smell of unwashed genitalia, are outside - but they are well on the way to wankered, and I have to push several pissed pensioners aside to reach the bar. My hand shakes as I take the beer. In 32 minutes I am due at the local hospital to receive test results. As the beer hits my tongue I am considering the shortened life, complicated drug regime and debilitating ailments that follow bad news. I am also considering that my pint cost £1.29.

In most London pubs it would be more than twice that much: an impossible price for those on the maximum state pension of £95.25 a week, and arguably a national disgrace. Yet it has fallen to the Thatcherite entrepreneur and Wetherspoons supremo Tim Martin to provide an affordable social drinking milieu for the over-sixties. Simultaneously, though I doubt deliberately, he has achieved something that proved beyond Stalin and the central committee of the Chinese Communist Party, or Hugo Chávez today - socialism.

Here in Tooting, I am happy witness to a people's democracy of cheap drink. Black, white, brown or yellow, all are united by bottles of obscure Polish lager, pints of dark, swirling scrumpy and giant Californian reds at ridiculous prices. This new social class has a revolutionary creed - as I discover when I drain my beer and look at the clock, conscious that doom awaits.

“Right, mate," interjects a smallish pensioner in brown slacks, white trainers and a red T-shirt bearing the words "Born to Funk" (I presume his wife does the charity shopping and has a cruel sense of humour). "What's it to be, then?"

“Yeah," chips in his pal, equally old and apparently still dressed in his bedwear, "what're you having?" They are not, I guess, economic theorists by trade, but these men have reversed everything we are told to believe about markets and motivation. They don't want to extract maximum financial value for themselves from their next transaction with the barmaid - they want to extract it for me, a total stranger.

There follows as good a time as it is possible to enjoy under the threat of fatal disease in south London while keeping the company of at least one 79-year-old wearing carpet slippers in a public place. Some time later - much later, it turns out - I leave Wetherspoons and stride into the consultant's room. "Right, doctor. What's it to be, then?"