The business lunch can be blamed for a growing number of bankers wishing to cover up their "larger bottoms" by wearing jackets with double vents, the survey found. Sixty-one per cent of bankers questioned said they preferred double vents.
Lawyers, on the other hand, appear to have cut down on wining and dining as 70 per cent of those surveyed opted for single vents "to flatter their honed waistlines".
Norton & Townsend discovered that different City professions each have their own unofficial uniforms. "London's bankers, stockbrokers, book publishers, lawyers and accountants conform to strict but very different dress codes," the survey said.
Of the bankers questioned by the tailor, 75 per cent wore plain coloured, single-breasted suits to work, with blue and grey the most popular hues. Matthew Norton, managing director of Norton & Townsend, said that the conventional suits worn by bankers were "very much a low-risk option guaranteed not to offend colleagues or clients".
Stockbrokers were found to be more adventurous than bankers, with 31 per cent of those surveyed choosing birdseye rather than plain cloths, and 25 per cent picking pinstripes. An overwhelming majority - 81 per cent - of stockbrokers wore turn-ups and double-breasted suits, as "one way of showing self-confidence", Mr Norton said.
Publishers were, surprisingly, less flamboyant. Seventy per cent of those approached wore single-breasted suits, and 50 per cent chose "sombre grey linings".
Grey was also the colour of choice for the accountant. But Mr Norton said there were signs accountants were trying to break free of their staid image by wearing more outgoing designs. Seventy per cent sported double- breasted suits with pin or rope stripes.
Accountants may have been inspired by New Labour's penchant for double- breasted suits, Mr Norton suggested. "If you look at New Labour, double- breasted suits have been recommended by the spin doctors."
Norton & Townsend, a visiting tailor which specialises in made-to-measure suits, surveyed 200 people working in central London. The company was, however, unable to draw any conclusions about what women wear at work.
Mr Norton explained: "Women are much more fussy in terms of cut. There aren't any visiting tailors which cater for women, as it's a difficult market."