Leading article: When the cowboy of the British class struggle runs out of road

There have been times in recent days when John Prescott looked unlikely to survive the week in any of the three roles he salvaged from the last Cabinet reshuffle: Deputy Prime Minister, deputy leader of the Labour Party or national buffoon. In the event, and by the skin of his teeth, he has so far managed to hold on to his official positions. It is as national buffoon that he has been ousted, and not a moment too soon.

Ever since Tony Blair became Prime Minister, Mr Prescott has traded to great effect on his status as a true Labour, working-class lad made good. In this guise, he has done Mr Blair the immense favour of lending a proletarian tinge to what have been rather middle-class Cabinets. When things have gone wrong for him - as they have - we, the voters, have tended to laugh them off as just the latest instance of Prezza-buffoonery. Mr Prescott, and others on his behalf, played the class card the other way. The Deputy Prime Minister, they insisted, was just being picked on - for his roots, his accent and his original use of the English language.

Both arguments, of course, deliberately neglect the fact that, as a politician, Mr Prescott is as canny as they come. He would not otherwise have lasted as long as he has. He knew well how to exploit his public image. Far from being a liability, his perceived class was an asset, a trusty shield against attack from enemies within the party and without.

There is great poetic irony, therefore, in the nature of his latest scrape - which should surely be his last. Simple, honest John has been caught hobnobbing with a right-wing American billionaire and accepting the hospitality of his luxurious ranch. Our working-class hero apparently saw nothing wrong in this; neither - shockingly - did the (unnamed) civil servants who accompanied him.

That the billionaire concerned had acquired London's redundant Dome and was interested in a slice of the New Labour mega-casino business was completely incidental. At least this is what Mr Prescott and his allies argue. The Deputy Prime Minister, they say, had no responsibility for the Dome, none at all for casinos and, even if he at one time had some say in planning matters, this was irrelevant here. Which, if true, encourages us to ask precisely what real responsibilities Mr Prescott exercised even when he had a ministerial portfolio.

The point, though, is less what Mr Prescott and his host, Philip Anschutz, may have discussed at the ranch - in addition, of course, to William Wilberforce. This is one time when it is appearance as much as substance that matters. What was the Deputy Prime Minister, the Government's official number two, thinking of when he accepted this invitation? Or, put another way, why did he think the Bush-supporting Mr Anschutz had invited him? Inspecting sugar beet production and indulging a childhood desire to visit a real American cattle-ranch do not constitute sufficient explanation.

Yet again we find a member of the Blair Cabinet whose moral compass seems to run amok when in the vicinity of serious wealth. From the Prime Minister and Bernie Ecclestone, to Peter Mandelson and his mortgage, to David Blunkett's nanny's visa, Tessa Jowell's houses and the Blair family's holiday arrangements, we have watched ministers who came to power vowing to sweep away Conservative sleaze, creating a culture of sleaze all their very own.

It is not their class that New Labour ministers have betrayed, but the voters who were promised better. As for Mr Prescott, he has ceased to be a laughing stock. His prowess as class-warrior should not give him a free pass out of this embarrassment.