Class conscious - Andrew Martin declines to wear the T-shirt

Nowadays, a T-shirt is standard wear for the non-posh British man at leisure

I was spending a night at a good hotel in Manchester when I stepped into the corridor at the same time as the man in the room next door. He was small, fat, had tattoos all over his arms, and was wearing a T-shirt emblazoned with the word "CRIMINAL", which was presumably a double bluff, in that anybody who actually was a criminal wouldn't wear a T-shirt announcing the fact. I wondered whether, dressed like that, he was getting the same treatment as I was, in my admittedly slightly threadbare suit: all the cheerful "Good mornings" from the staff and ready offers of assistance at the reception.

I'll bet he was, because a T-shirt is standard wear for the non-posh British man at leisure, even on the coldest days. Two minutes before seeing that man, I'd been listening to the wind howling outside my hotel-room window, and it generally seems to me that popular styles of dress now take no account of cold weather at all.

On a Saturday night in York, in Micklegate, where most of the pubs are concentrated, you'll see lads and lasses lurching in gangs from one boozer to the next on what's called the "Micklegate run". Even in, for example, a heavy snowfall the average lass will be wearing a miniskirt and skimpy top, and the average lad will be wearing jeans and a shirt. They like to travel light, these youths, carrying only the absolute essentials: cash, packet of fags and mobile phone/digital camera, all of which, in the case of the lads, can be crammed into the top pocket of the shirt. By the way, when in the wrong hands - which they always are - these digital cameras can be a real menace. Earlier this year, I was drinking in a northern pub with a man who has quite a big bottom, and this, I noticed, was being carefully photographed by one of the four peroxide blondes at the adjacent table. (Little did the man know it, but it seriously detracted from the gravitas of his conversation.)

The last time I was in Micklegate on a Saturday night, I was wearing an overcoat, being middle-aged, middle class and cold. A gang of lads came towards me, and I braced myself for abuse. They looked me up and down, taking in the coat. "Student!" one of them declared. It was the only way they could rationalise the coat, and I was quite flattered - they didn't say "mature student", after all.

In Edwardian times, working men wore suits to dig holes in the road. Women wore long skirts and underskirts, and the sound of the material rustling was considered sexually attractive, whereas today this auditory component of sexuality has entirely died away. By the late Sixties and early Seventies, working-class women were starting to dress down before a night on the town (miniskirts were in), but men were still dressing up. In Barry Hines's book A Kestrel for a Knave, Billy Casper's coal-miner brother, Jud, puts on a suit before hitting the pubs ("Some bird's goin' to be lucky tonight").

But it was inevitable that men would join the women in the movement towards near-nakedness. The main factor is the increased frankness of British sexuality, but another is the omnipresence of central heating. Who wants to be in a hot nightclub wearing a jacket? It leads to expense (paying for storage at the cloakroom) or fights: "'Ere, mate, you're sitting on my jacket." A second is the rise of the service economy, in which young people are normally required to look smart. If you're a 22-year-old estate agent, chafing against an M&S two-piece suit from Monday to Friday, you'll naturally go for a casual (that is, half-undressed) look come Saturday night.

As for me, I wear a jacket all the time, only I'm thinking of calling my jackets coats, as the late Duke of Devonshire did. Apparently it's the classy thing to do.