“I am sorry, Mr Brown, but I cannot agree to a dissolution and a general election. The present Parliament is still less than half way through its five-year life. You said last spring that a new prime minister did not need to go to the country and you command a good working majority in the House of Commons. So I am afraid you will have to wait.”

Imagine the sensation if the Queen said “no” in a Helen Mirren-like tone when Gordon Brown visits Buckingham Palace next week for what he expects will be a formality.

There is no need for a general election now. The only reason is the belief of Mr Brown’s advisers that Labour is more likely to win now than next spring or later.

The Queen will not, of course, refuse; such dramas occur only in the works of thriller writers such as Michael Dobbs. The monarchy has not refused a prime minister’s request since the 19th century and its guiding principle has been to stay out of party political controversy. Moreover, opposition parties have now publicly called for an election. Describing an early contest as a “constitutional outrage”, Sir Malcolm Rifkind fantasised that a refusal “would probably be the end of the monarchy, but what a way to go”.

There are precedents. In 1951, 1966 and 1974 - with each election called within less than two years of the previous one - the incumbent party had a small Commons majority, much smaller than now. In spring 1955 Anthony Eden called an immediate election after being appointed Prime Minister, though this was three and a half years after the previous contest. So Mr Brown is exercising to the full the prime minister’s discretion over the choice of an election date, one of the most powerful weapons in his armoury. He conceded in his Governance of Britain Green Paper only three months ago that the power over the election date gives “the prime minister significant control over Parliament”. He then proposed creating a new convention so that a prime minister “is required to seek the approval of the House of Commons before asking the monarch for a dissolution”. This change has not yet been agreed, but will Mr Brown honour its spirit next week by holding a debate before seeing the Queen?

The proposal is mainly an empty gesture since any prime minister with a clear majority will always be able to obtain MPs’ consent. It is a meagre change compared with the position in most other countries: all presidential, and most parliamentary, systems have fixed terms, set legally or by convention.

Early elections are not risk free. Voters are suspicious of suggestions of a “cut and run” contest earlier than expected. They fear that things are going to get worse rather than better, a feeling that could be fuelled by the gloomy forecasts coming out of America and the expectation of tighter economic conditions here next year. Voters wonder if Mr Brown knows something they do not. For all the confidence of some of Mr Brown’s team, they should not just study the polls but also remember how the governing party was punished in 1970, February 1974 and in the French legislative elections of 1997.

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