With his brilliant mind, impeccable good manners and lovely family, Abhisit Vejjajiva – or “Mark Vejj” as he is known to his British chums from Eton and Oxford – sounds like an almost painfully decent chap. He would make an ideal best man, a dreamy son-in-law, and a perfect dinner party guest. But how will he fare as prime minister of Thailand, a country lurching from a position as one of the most stable to one of the most chaotic in southeast Asia?

The route by which he came to power does not inspire optimism. In fact rarely, since the days of Dr Faustus, has a thoroughly good egg achieved power through such grubby and disreputable means.

Mr Abhisit has been leader of the Democrat Party since 2005 in which time there have been two general elections. He boycotted the one in 2006, which was won, for the third time in a row, by Thaksin Shinawatra’s Thai Rak Thai party. Last year, he was defeated decisively. However well liked he is by his Etonian friends, the majority of Thai voters have pointedly chosen someone else whenever they have been given an opportunity.

Mr Abhisit owes his new job, not to any democratic mandate, but to the support of powerful friends – and even they have required multiple attempts to propel their nominee to power. There was the army, which drove Mr Thaksin from power in 2006 in a bloodless coup. There were the tame delegates, who rewrote the constitution at the generals’ behest, to give Mr Abhisit a better chance of winning. To their dismay, he lost again in 2007. Cue Mr Abhisit’s new best friends, the People’s Alliance for Democracy (PAD).

At various times, Mr Abhisit has had the decency to appear slightly embarrassed by this mob of yellow-shirted anti-Thaksin activists, who first drove the Prime Minister out of his own office, then closed down Thailand’s international airport last month. Even this wasn’t enough to shift the Government. It fell to the country’s Constitutional Court to deliver the coup de grâce, with a judgement dissolving the ruling party – which many Thais believe to be influenced by political considerations.

But even then, Mr Abhisit couldn’t have grasped his prize without the support of turncoats within the ruling party – the same men whom the Democrat Party had been denouncing for years as unfit for office and with whom they will now form a government. As the leftwing Thai academic Giles Ungpakorn put it yesterday: “The Democrat Party is known among the cyber community as the ‘Cockroach Party’. This is because cockroaches live in filthy places and can survive even nuclear holocausts.”

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