Mary Dejevsky: A fiasco that shows British diplomacy is clapped out

If, as it appears, yesterday's EU summit spelled the end of Tony Blair's undeclared ambition to be the first President of Europe, you have to ask whether he really wanted the job at all. So clumsy and ill-prepared was the campaign that, with hindsight, it almost looks like a manoeuvre to exclude him – and clear the way for David Miliband to bid for the post of High Representative.

But the failure is not cost-free to Britain; the wreckage left behind is considerable. It is not just in the arcane world of EU diplomacy, but in the diplomatic world generally, that the cardinal rule is to ensure the invitation will be accepted before you send it. Neither as a nation, nor as a minister, do you put your head above the parapet until you are pretty sure of a favourable reception. You quietly check the lie of the land; you sound out trusted intermediaries; you do nothing that would risk losing face.

Now, this is exactly what has happened. Tony Blair might not actually have stood on his soapbox, but he did absolutely nothing to stop his bandwagon once it started. Why it started when it did remains a mystery. But the far greater mystery is why on earth the Foreign Secretary and then the Prime Minister came out to lobby so enthusiastically and publicly on Mr Blair's behalf, even before the Lisbon Treaty was ratified.

It would not have been hard to discover that opinion within individual EU states was, to put it mildly, unconvinced by the merits of Mr Blair. Most journalistic outlets teased this out days in advance. Why did Britain's diplomats in Brussels not pass the message to London – or, if they did, why were they ignored?

The conspiratorial explanation might be that the Foreign Office saw its interests as being better served by Mr Miliband remaining in the contest for High Representative, than by Mr Blair becoming President, and tailored its efforts to that end. But there are other possibilities.

One would look like a sad repeat of the doomed Second Resolution at the UN, when the Government's one-track thinking on going to war with Iraq led it to underestimate opposition at the UN. Or could it simply be that, even after 12 years in office, this Government still hasn't figured out how Brussels really works? Either way, the diplomatic machine once described as a Rolls Royce looks closer this week than last to qualifying for scrappage.