The fevered speculation about whether Gordon Brown will call an early election is the best possible illustration of why the prime minister should not have the power to decide the timing of a British general election.

Britain had its last general election barely two years ago – and that election was a year early. Turnout was the lowest in modern British history. The two facts may not be entirely unrelated.

Other countries – and the Welsh Assembly and Scottish parliament – have fixed parliamentary terms. The Welsh and Scottish first ministers do not have the tactical advantage of calling an election for their own political gain.

True, prime ministers have occasionally been embarrassed by getting the timing wrong. Jim Callaghan famously made fun of the electorate by hinting at an election in 1978 and then said he was not going to the country. By the time the election was actually held in May 1979 the winter of discontent destroyed Callaghan’s reputation and Margaret Thatcher swept to power. Nine years earlier, Harold Wilson called an early election and was surprisingly defeated. (A defeat allegedly prompted by a balance of payments deficit caused by BOAC’s order for the first 747 jumbo jets.)

But doesn’t Gordon Brown have a duty to ask the people for a mandate? No. We live in a parliamentary democracy. There is no need for an election when the ruling party changes leaders. It was clear in 2005 that Brown would become prime minister during this parliament. The people made their choice. We don’t need to be asked the same question again.