Suits you, sir, but button it

It shows a distinct lack of class to wear an open jacket

There is one very important thing that has been completely ignored at the recent Labour and Conservative party conferences. There may or may not have been tension between Cherie Blair and Gordon Brown, and David Cameron may or may not lead the Conservatives to victory, but the detail that overshadowed almost everything else for me was the quite gratuitous flapping of jackets.

It is natural and acceptable for a gentleman to undo his jacket when he sits down, otherwise it will billow out like a puffer fish. But when standing up again, a man should always do himself up, just as he does up his trousers after visiting Mr Toilet. It is extremely bad manners to stand up or, worse, walk around with a suit jacket undone. This harks back to the days when showing shirt-front was not acceptable behaviour. Only your parents or your bedfellow should ever get to see it.

With a proper single-breasted jacket - that is to say, a three-buttoned jacket - it should only ever, to be absolutely correct, have one button done up: the middle one. (Double-breasted jackets follow a completely different set of style rules that we shall cover if ever the Conservatives get back into power.) To do up any more, or fewer, is a crude fashion statement that is frowned upon by suit purists.

Doing up only the middle button can, admittedly, look odd at first. To ease yourself in, you can just about get away with doing up the top and middle buttons. According to the suit-wearing scriptures, this hints at a certain flirtatiousness, which is no bad thing in the right circles. However, to do up only the top button shows an indifference to dress, as well it might: this is a very shoddy approach. Doing up only the bottom button hints at a lowly affectation. The kind of man who does this usually appears on a Wanted poster before very long.

However, as we witnessed at the party conferen ces, politicians have introduced another option: going "politico". This involves not doing up any buttons at all. Not buttoning up on standing up hints at two things: laziness and arrogance. It takes only a second to slip that middle button into the buttonhole; but some politicians are in such a rush to get their message across - because, of course, it's so important - that correct presentation goes out of the window.

Cameron, Brown, Tony Blair and the unctuous George Osborne were so very keen to get their point across that they all exposed themselves. Boris Johnson, too, but I think he does it for entirely different reasons, in that he seems like a man who has only just learned to dress himself - so we must forgive him. Cameron actually went on a BBC walkabout with his jacket undone the entire time. I didn't hear a word that was said, because I spent the whole time sucking my teeth in disgust.

Do these people not have time to watch old movies and see how it should be done? I can recommend one that illustrates beautifully how a suit jacket should be treated: Alfred Hitchcock's North by Northwest. In this film, not only does Cary Grant wear a light grey suit extremely well (this colour suit has all but disappeared these days), but he is correctly buttoned at all times. It is inspirational.