WITHIN one generation the City of London has changed beyond recognition.

Thirty years ago, City men wore pinstripes and bowlers and carried brollies as they waddled penguin-like to their long lunches.

Now City men have grown younger and become City persons; and the old uniform has been discarded in favour of the Armani suit, jazzy tie and mobile phone. The long lunch is gone too: nowadays the young workaholics arrive at the office by seven in the morning and sit gazing into their computer screens for hours fortified only by cappuccino or straight black from Starbucks.

In the good old days - sorry, I mean the bad old sexist, old boy networked, colossal deals done over three hours at the chop house to the accompaniment of large steaks, sticky toffee puddings, pints of claret and bushels of Taylor's Vintage days - there was a deceptive indolence at the office. Much work was done, but it was regarded as ungentlemanly to think of what went on as work.

Nowadays the fashionable youngsters aiming to make their first £5m before burnout, sit shirt-sleeved in front of their terminals and quit that position only to step outside for a smoke break. In the old, unenlightened days when gentlemen were either Senior Service or Capstan Full Strength and passive smoking had not been discovered, everyone chain-smoked throughout the day in the oak-panelled offices. Old City gents associated cocaine only with a trip to the dentist.

Now the dealers sit in open-plan trading rooms as vast as football stadia. The old gentlemen would have found it deafening, but such decibels are nothing to youngsters who spend their nights at the nightclub disco.

The outdoor uniform of the new City person involves a black overcoat, usually worn open. To walk down Cheapside is to imagine you were at a series of posh funerals. The women City persons wear black too and they are groomed so expensively they look as if they are on their way to a State Opening.

The talk is about clothes, celebs, clubbing, restaurants, soap-operas and holidays in rare places. These holiday destinations go in and out of fashion. Last year it was Vietnam. This year it's the Galapagos Islands - or is it the Great Wall of China? Skiing is forever - though Switzerland is pass.

Their conversation is like constipation: sluggish, unmentionable. The subject-matter all empty-headedness, as if they spent their whole lives on the pages of a fashion mag. Yet they feel so superior. The sheer arrogance of ignorance. And then there is the accent and intonation: not only "fings" and "finks", which just might pass for the dregs of ancient Cockney, but the upward inflection at the end of every gobbet - a habit they have picked up from the Aussie soap operas. They all have the bearing and, worse, one suspects, the aspirations of a twelve-year-old. The City has regressed to childhood.

* Peter Mullen is Rector of St Michael's, Cornhill, in the City of London, and Chaplain to the Stock Exchange.