In Southwold, Suffolk, there's a clothes shop called Denny's that a century ago harboured 20 resident tailors – I believe they had their own cricket team. They must all have been turning in their graves on Sunday, when almost every man in the town was wearing shorts.

Shorts are "on trend", which makes me despair of British manhood. But, at the same time, suits are also on trend, which makes me think there might be some hope for British manhood after all. According to a documentary, The Perfect Suit, which is on BBC4 on Wednesday week, Top Man is selling more suits now than ever. Mad Men could be a factor.

The documentary is an enjoyable history of the suit and the presenter, Alastair Sooke, receives some memorable advice from tailoring sages – "If there are two buttons on the suit coat, never do them both up, or you'll look like a newscaster" – but it would be fair to say that he reaches no firm conclusion about the perfect one. I myself have been looking for 30 years, encouraged initially by my dandified father. He had plenty of suits from Burton, one of the "multiple tailors" serving the clerks of mid-20th-century Britain: the suit was measured and cut by hand, but sewn together in a factory. He also had some entirely bespoke suits and, when I was 18, he took me to the tailor who had made these.

I was duly measured up – "The greyhound breed, just like your father!" – and when, a month later, the tailor handed me the finished product, he said: "Lucky suit for you, sir!" The next day I fell off a motorbike while wearing it and the day after that, I limped back in with the bloodied trousers, asking for a new pair to be made up. The tailor was aghast. I never hit it off with him as my father had and when I went back to him 30 years later with a pin-striped suit I'd bought for a tenner in Oxfam, in order to ask him how much it would cost to duplicate, he gave me a peculiar look. It was not the "rock of eye" by which tailors recall immediately the measurements of their customers. It was a more general assessment along the lines of: "You have not grown into the sort of man who can easily afford a bespoke suit," and he dismissed me pretty smartly from his shop.

A bespoke suit will indeed usually cost over a thousand pounds, so I stick with off-the-peg. I have a dozen suits, the rationale being that if you are going to dress in a fairly generic way, then it is more honest to wear clothes that are supposed to look generic rather than ones meant to look iconoclastic.

The dominant social trend of my life has been towards informality and I feel vindicated in having resisted, since it culminated in the chinos and loafers of the Blair years, a style now associated with an ingratiating manner screening duplicity. (Another consideration is that 20 years ago, I introduced myself to an astringent middle-aged woman at a party in Notting Hill as "a freelance writer". "Mmm," she mused, "...often a euphemism for unemployed." So my suits are meant to make me look less unemployed.)

But if it's hard to find the perfect one in winter, it's harder still in a hot summer. I used to favour unlined linen suits, with a good-quality collarless shirt and I was so attired last summer when I literally bumped into the extremely dapper Bill Nighy in Jermyn Street in central London.

Less than a fortnight later, I read an interview with Nighy, in which he said that on no account should a man wear an unlined linen suit and a collarless shirt just because they happen to keep him cool.

An elegant suit needs weight, but we have lost the doughtiness of our forebears, who could stand the heat much better and fought colonial wars in the thick, red woollen coats that the British Army uniform then involved. In its determination to keep cool at the expense of elegance, my generation of males has apparently drawn the nemesis it deserves: global warming.