The last British prime minister to dress comme il faut was probably the ill-fated Anthony Eden, who succeeded Winston Churchill. His widow stated in an interview that the first thing she noticed about him were "his beautiful clothes."
It is interesting to note that: (1) he was not regarded by his contemporaries as a 'serious' man and (2) having waited (impatiently, by all accounts) a lifetime for Winnie finally to retire, he lasted 21 months as prime minister (although, in fairness, he did have to contend with the 'Suez crisis').
It is likely that Eden was thought by some 'stinkingly stylish'; that is to say, conspicuously well-dressed. Remember: this was England; WWII well within living memory, rationing (of food and clothes), which continued long after the cessation of hostilities, cold, damp and grey. And there, in the midst of all this post-war austerity, was the patrician Eden, whose clothes did not go unnoticed. None of which is surprising: why, the man even wore shiny mohair!
The point is that Eden could get away with it: he was blue-blooded, people knew 'their place' and their place was well-below the vantage point occupied by their 'betters'.
In a political world lead by opinion polls, sound-bytes, media presentation, etc, I find it hard to believe that front-row politicians' dress is not very, very carefully thought through; I can only conclude that the results are a careful compromise designed to give the least offence to the greatest number.
It is I think naive to suppose that (British) politicians - or any other man, for that matter - simply don't care about their appearance: men make choices when they dress each morning; they may not get it right, but they CHOOSE.
Tony Blair
Where to begin? Well, if you think he looks poorly attired at work, you ought to have seen him on holiday in Tuscany one August: white pants, white linen shirt (dehors pants, of course; he is British, after all) and BLACK SHOES!
Tony at work? He looks like any other non-descript free-world politico. I do however have the following (minor) cavils:
(1) am I alone in thinking that he could slick his hair back in a more dignified manner, as befits a PM? (Leave the - albeit, less exaggerated - tousled look to footballers, Kenneth Cole devotees and Soho hotels personnel)
(2) can anyone explain to me why he opts for centre vents? It is decidedly not British. Perhaps this is the first stage of transmogrification - from Blair to Bush.
(3) I cannot believe, as some have suggested, that his suits are made by Henry Poole & Co.
(4) I am informed that he is a devotee of Marinella ties: this is surely defamatory of Maurizio Marinella.
In sum: he looks crap, but the nation expects no more or less.