If you wanted to see why Tony Blair is finished as a force for good in politics, you should have been at the discreet, if extortionately expensive, Haymarket hotel, off Trafalgar Square. Portland Communications, publicists for what it calls "the government of Russia" and everyone else calls "that thieving bastard Putin", was holding a dinner for journalists and politicians it hoped to seduce on behalf of one of its many other clients.

Blairites headed the guest list: Lord Adonis, who has re-emerged as Ed Miliband's adviser on industrial policy; and James Purnell, whom the Labour right see as the king over the water who will one day return and restore Blair's heirs to their rightful inheritance.

In showing no disdain for the mouthpieces of a dictatorship, Adonis and Purnell were doing no more than following the example of Blair and his circle. Portland Communications is at its heart. Tim Allan, Blair's former media adviser and Portland's founder, recruited his old friend, Alastair Campbell, last week. A few months before, a Financial Times reporter spotted Campbell at the airport at Astana, the capital of Kazakhstan. He wondered what had brought Campbell from his London home to a flyblown central Asian dictatorship. Campbell would not say if his visit had anything to do with Blair's latest business dealings. Few would be surprised if it had because Blair's dealings are extensive.

As one astonished and disgusted former supporter put it: "If you want to know what price a great man will sell his legacy for, it's $13m." According to the Financial Times, that is the sum that President Nursultan Nazarbayev has paid for Blair's services. His old gang is along for the ride and eager to see what an oil-rich dictatorship, which shoots strikers, burns the offices of opposition parties and kills their leaders, can offer.

As well as the enigmatic Campbell circling the carousels at Astana airports, a spokesman for Portland told me that it was "reforming Kazakhstan's communications". Sir Richard Evans, formerly of BAE Systems, who was once described as "one of the few businessmen who can see Blair on request", now chairs the £50bn Kazakh state enterprise Samruk and it in turn hires Peter Mandelson to deliver speeches.

The regime is grateful and not just for the uses the Blairites' support can be put to abroad. Like every other dictatorship, Kazakhstan wants to show its subjects that foreigners, who have no reason to fear the secret police, endorse the regime of their own free will. The backing of outsiders makes them seem more powerful and their propaganda sound more plausible. (It is for this reason that George Galloway has been such a popular figure in the presidential palaces of the Middle East.)

I know what you're thinking. Blair selling out is hardly news. But – and Observer readers may not provide the most sympathetic audience for this argument – there was always a case for Blair. His dedicated adherents could see no wrong in whatever he did. But others, including your correspondent, were, if you will, "left" or "anti-totalitarian" Blairites. Whatever criticisms of his domestic policies we had, we thought that when set against his enemies, Tony Blair was an admirable man.

Historians trying to capture the hypocrisy of Britain in the first decade of the 21st century may note, as we did, that Blair's opponents turned on him not for allowing the banks to run riot but for insisting that Britain should play its part in stopping the civil war in Sierra Leone, in ensuring that Slobodan Milosevic could not ethnically cleanse Kosovo, in helping throw the Taliban out of Kabul and in saying that after 24 years of occasionally genocidal rule, Saddam Hussein must be removed from power.

Let one example from countless instances of bad faith stand as an example of how sour polite society became. In 2007, John Humphrys of the BBC interviewed Blair about the oppression in Iran.

Blair: "There is global struggle in which we need a policy based on democracy, on freedom and on justice…"

Humphrys: "Our idea of democracy?"

Blair: "I didn't know that there was another idea of democracy…"

Humphrys: "If I may say so, that's naive…"

Blair: "The one basic fact about democracy, surely, is that you can get rid of your government if you don't like them."

Humphrys: "The Iranians elected their own government and we're now telling them…"

Blair: "Hold on, John, something like 60% of the candidates were excluded."

I do not pick on Humphrys because he was an exceptionally wicked man, but because his approach was so depressingly commonplace. Iranians and other lesser breeds could not expect the rights we enjoyed, and it was "naive to think otherwise". Blair replied in admirably plain language. His commitment to democracy and human rights was absolute. Moreover, it was universal: if free elections are good enough for Britain, they are good enough for Iran and no weasel words about theocrats having their "own" version of democracy can be allowed to pass uncontested.

By necessity, Blair was also an internationalist, because, as he said in his Chicago speech of 1999, which was by some measure his finest: "We are all internationalists now, whether we like it or not… we cannot turn our backs on conflicts and the violation of human rights within other countries if we want still to be secure."

His back is turned now and the plain speaking has gone. He won't explain why he's helping the Kazakh dictator present a better face to the west. Apparently, he has said that he is not personally profiting from appearing in a propaganda video praising the dictatorship's "progress" and hymning its "extraordinary economic potential". (I say apparently because his office would not respond to my repeated inquiries.) But it is beyond doubt that his commitment to democracy is now as flimsy as any relativist's: free elections may be good enough for the people of Britain, but the Kazakhs cannot expect to enjoy the same privileges.

Blair's mindless admiration of wealthy men explains his decline. In the 21st century, they tend to be dictators with sovereign wealth funds and tame oligarchs to command, or financiers. No surprise, then, that as well as advising Kazakhstan, Blair also advises JP Morgan.

His love of money has brought down the worst fate that could have befallen him. He now has the manners and morals of his opponents. He has become a George Galloway with a Learjet at his disposal.