SOMETIMES, and it seems increasingly these days, a piece of political spin is so utterly irritating that it prompts an overwhelming compulsion to exclaim an opinion on it.

Think of the figure depicted by Norwegian painter Edvard Munch in The Scream and you will get the idea.

There was such an instance on Wednesday night when reading about Chancellor George Osborne's comments at the Mansion House in London. He talked about the UK Government potentially getting less back for its majority stake in Royal Bank of Scotland than his predecessor, Labour's Alistair Darling, "paid" for it.

A quick subsequent check on the full text of Mr Osborne's speech on the Treasury website found the word "paid" featuring three times in the context of RBS. This is, quite frankly, ridiculous.

Mr Osborne is perfectly entitled to choose when he wants to start trying to sell the UK public's stake in RBS. And you would perhaps expect, given he is a politician, that he would make a big deal of firing the starting gun on what is likely to be a long and difficult process.

In the week before the speech, it had been spectacularly well trailed that Mr Osborne would spell out his plans to try to get RBS fully back into the private sector. So many column inches had been devoted to it that, were it not for the sake of form, you might argue that Mr Osborne did not really need to turn up at the Mansion House to deliver the speech.

For all the advance trailing of what Mr Osborne would say, RBS shares still managed a 1.9 per cent gain yesterday on the back of the Chancellor's confirmation of his plan to start selling down the Government stake in the Edinburgh-based bank "in the coming months". Such is the way of things in supposedly efficient financial markets.

Mr Osborne told his audience the £45 billion that the Labour Government put into RBS represented the "largest single bank bail-out in the world". This bail-out came after the collapse of US investment bank Lehman Brothers in autumn 2008 caused the global financial crisis to take a lurch for the worse.

The Chancellor said: "I was not responsible for the bail-out of RBS or the price paid then for shares bought by the taxpayer but I am responsible for getting the best deal now for the taxpayer and doing whatever I can to support the British economy."

Mr Osborne is right. He was not responsible for the bail-out. That said, the RBS rescue does still look like a very fine piece of emergency action by Mr Darling and then Prime Minister Gordon Brown to prevent a much greater crisis

In his speech, Mr Osborne said: "Do we begin the process of selling down the Government's huge majority stake, even though the share price is still below what the last Chancellor paid out seven years ago? Or, do we hope against hope that something will turn up?"

He went on to say that he believed it was right to start selling the stake, and noted this was also the judgment of Mark Carney, the man hand-picked by Mr Osborne himself to be Governor of the Bank of England.

However, Mr Osborne must surely know Labour did not, even stretching the definition of the word to its absolute limit, "pay" in any conventional sense at all for the stake in RBS. Rather, it ended up with the holding as a result of an injection of taxpayer funds to save RBS from collapse.

A failure of RBS would have had horrendous consequences not just for the UK financial sector but for the whole country. The decisive action of Messrs Brown and Darling to bail out RBS and Bank of Scotland parent HBOS, which is now owned by Lloyds Banking Group, might be recognised in economic textbooks of future decades as a key move in bringing the UK back from the edge of the abyss amid the global financial crisis.

While apparently a bit sketchy on the history, at least Mr Osborne does seem to have an awareness of the challenges involved in selling the RBS stake.

He said of RBS: "Its problems and its slow recovery have been one of the biggest drags on our economy, as many smaller firms know all too painfully."

And he admitted that sales of the Government stake in RBS would "take some years", likely involving all types of investors.

In spite of such morsels of reality in Mr Osborne's speech, spin and political posturing were the key elements of his appearance at the Mansion House.

He put forward proposals to legislate to prevent a future government from running a budget deficit "in normal times". Just who does Mr Osborne think he is, by trying to dictate how as-yet-unelected UK governments should run the economy?

This criticism is not based on his own economic shortcomings, which are manifold. Rather, a future government must have the freedom and all the levers at its disposal to do as it sees fit.

If it wants to run a budget deficit in a given year, so be it. Why would you put in place yet another rule to hamstring policy-making in a democracy, rather than allow future governments chosen by the UK electorate to run the economy, hopefully in line with the mandate they have been given?

This is obviously a political manoeuvre by Mr Osborne, perhaps even with the idea of creating some sort of legacy. It seems about as bad as the lamentable cap on welfare spending. And it is clearly a continuing effort to paint a picture of the Conservatives as a party of economic responsibility.

All this from a man who is about to demonstrate some real economic irresponsibility by implementing savage welfare cuts that will further suck the life out of a flagging economy. The Conservatives have been obsessed with the cost, rather than revenue, line as they have focused determinedly but with little, if any, success on the deficit.

And who will decide in future what are "normal" economic times? Perhaps the taxpayer could employ Mr Osborne as a consultant in future years to tell us.

Then again, the Chancellor has not appeared to be very good at characterising things.

With his proposal on banning budget deficits, he is once again attempting to paint a picture that, if Labour had spent a bit less, everything would be okay.

He blames the deep recession on Labour's economic policies rather than the global financial crisis that actually triggered it. And he seems to think Labour "paid" for the RBS stake, as if it were a normal share purchase.

It is almost enough to make you want to scream.