Steve Richards: The last thing Gordon Brown needs now is a referendum on Scottish independence

Few referendums are held in the United Kingdom and yet the hope or fear of one being called leads to mayhem. They are the cause of some of the biggest storms in recent years, hovering around highly charged debates, policy areas that have the potential to transform everything.

The hovering is enough. Calm political leaders get in a desperate sweat over them: "Help, we will have to offer a referendum on this or we are dead!" Alternatively, neurotic leaders see them as a soothing device: "If we offer a referendum on this it will avoid a damaging split and we can postpone an awkward decision for another day." When it comes to holding them, referendums seem less soothing: "Help! How do we get out of this?" The one thing that rarely happens in these dramas is a staging of a referendum.

There is another constant. Whenever a plebiscite is offered, there is more to it than meets the eye. Such an offer does not represent a sudden outbreak of concern to widen the power of the electorate. The move is made always with a thousand nerve-racking, sweaty, self-interested calculations.

Of all the offers of a referendum, the most astonishing is this week's intervention from Wendy Alexander, the Labour leader in Scotland. Suddenly Ms Alexander has declared in favour of a poll on independence, a move that makes the cliché "high risk" something of an understatement. The proposal comes more or less out of the blue. In Scotland an independent commission is currently looking at the devolution settlement, analysing whether more powers should be devolved. It is not expected to report for some time. Suddenly the context in which the commission deliberates is changed. The debate moves on, or returns, to the oldest question of the lot: independence – yes or no.

Ms Alexander's move means that the Scottish parliament in theory at least now has a majority for the first time in favour of a referendum. At Westminster ministers are baffled and alarmed. As one told me: "We put a question to voters last Thursday and they gave us a very clear answer. This is hardly the time to put another question to the voters."

By implication, he was raising one of the fundamental problems about referendums. Voters give their verdict partly on the basis of who they wish to kick. In Scotland voters gave Labour an almighty kicking a year ago when they elected a minority SNP administration. As is the case in the rest of the country, the anti-Labour mood has deepened since then. This is not a time for Labour to be instigating a poll anywhere. The Crewe by-election is unavoidable. Ms Alexander is volunteering to hold a poll when there is no immediate need.

Although she is not quite doing that, or at least her intention, it seems, is different. In her conversations with Gordon Brown in recent months, the two of them have agonised over how to shine some light on the SNP's wily approach to the matter of a referendum. The First Minister Alex Salmond is also playing games with referendums. As every leader does, it is hardly surprising that the master strategist of our times does so as well. He has never been in a hurry. He waits for the best time to hold one, which, from his point of view, would be under a newly elected Conservative government at Westminster, or at a point where one looked inevitable.

Meanwhile, the issue hovers over Scottish politics. Partly Ms Alexander sought to cast cathartic light on the manoeuvrings of the SNP, but in attempting to be wilier than Mr Salmond she landed in an awkward place.

Bring on a referendum, she cries at a time when Labour loses elections on the same scale as it did in the early 1980s. For once, Gordon Brown is closer to Mr Salmond. As far as Mr Brown is concerned, the referendum can wait. The last thing he needs now is a make-or-break campaign on the union. If he were to lose it, the consequences would make the recent disastrous election results for Labour seem like a pleasant night out on the town.

There is a single, powerful case for holding a referendum soon, the reverse of Mr Salmond's calculations. Yesterday, I was talking in a Westminster corridor to a Labour peer from Scotland. When one of Mr Brown's close ministerial allies passed us, the peer told him that there should be a referendum soon because, if it looked for certain that the Conservatives were going to win the general election, a referendum would be lost and the UK would break up. The Cabinet minister replied that the Conservatives were not going to win, so the issue did not apply. We shall see. What is clear is that from the Government's perspective there is no appetite for another electoral contest of any sort in the near future.

I wonder still if the referendum will ever be held in Scotland. Precedent suggests something or other will get in the way. What a titanic moment it was in British politics when in 1991 John Major persuaded his Chancellor, Ken Clarke, to support a referendum on the Euro. Mr Clarke has regretted conceding the ground ever since, one of those moments when the Euro-sceptics proclaimed a significant victory. Of course the referendum was never held, neither by the Conservatives, nor by Labour who also offered one.

In the build-up to the 1997 election, Labour proposed a range of referendums to avoid taking thorny decisions in advance. Most of them were not held, including the one promised on electoral reform. There were further traumas as Tony Blair promised Rupert Murdoch that he would hold a referendum on the European Constitution. Again it was never held. But will the Conservatives offer a retrospective referendum on the Lisbon Treaty? I doubt if they will even offer it. I am sure they would never hold it.

Referendums are the clumsiest and least democratic of tools. Leaders only offer them when they think they can win. Quite often they are proposed to avoid an argument. Sometimes they are offered to make mischief. Mr Cameron still pretends he wants a referendum on the Lisbon Treaty in order to embarrass the Government, which was too scared to hold one because it would lose. Nick Clegg suffered a setback when he could not persuade all his MPs to oppose a referendum on the treaty, having to reach a compromise in which his party weakly abstained on Europe, traditionally one of its strongest points. All of this over a referendum that will never be held.

Little changes, on rare occasions, when one is held. In 1975 a Labour Prime Minister secured a big yes vote in favour of Britain's continuing membership in Europe. Five years later, Labour was committed to withdrawal from Europe.

In Scotland the dance over a referendum will have its own profound consequences. Already it makes waves down in Westminster. What precisely did Mr Brown know about Ms Alexander's ploy? What did she really want to happen when she said bring on a referendum?

It will be a long, hot dance in Edinburgh and London. Do not count on a referendum being held at the end of it.

s.richards@independent.co.uk