Hung parliaments are back on the political agenda.
With a general election less than seven months away and a couple of recent opinion polls showing Labour narrowing the gap with the Conservatives, there is growing chatter at Westminster that the Tories might not gain an overall majority.
After months in which it was assumed that David Cameron was assured of victory, increasingly seen as the Prime Minister-in-waiting, Labour suddenly senses it might be back in the game after all.
For the Liberal Democrats, a hung parliament holds out the prospect that they could be the king makers - determining whether a battered Gordon Brown could cling on to office or Mr Cameron would enter No 10 at the head of a minority Conservative government.
It is 35 years since a general election produced a hung parliament. In February 1974, the Conservative premier Edward Heath called a bleak general election on the issue of "who governs Britain" in the midst of a damaging miners' strike.
The verdict of the voters was "not you mate!" - though it demonstrated no great enthusiasm either for the return of the former Labour Prime Minister Harold Wilson.
As the final results dribbled in on Friday March 1, it looked as if the election could result in a dead heat, or with Labour or the Tories just ahead.
In the end, the Conservatives won the largest share of the vote, but a handful of seats fewer than Labour.
It is a scenario which could well be replicated next May or June - or even in March if Mr Brown decides to go to the country earlier than expected.
At the weekend, Nick Clegg, the Lib Dem leader, sensing a change in the political weather, said the party which got the strongest mandate from the British people "will have the first right to seek to try and govern either on their own or with others".
If the next election results in no party securing an overall majority, constitutionalists are likely to be dusting down a memorandum prepared after the February 1974 election by the then-head of Heath's private office, Robert Armstrong, now Lord Armstrong of Ilminster.
He was the government's chief contact with Buckingham Palace, keeping the Queen in touch with the coalition talks through her private secretary and exploring the role she might be called upon to play.
The 20-page memo, now lodged with the Margaret Thatcher Foundation, recounts the detailed negotiations that took place between Mr Heath and the then-leader of the Liberal Party, Jeremy Thorpe, over the weekend before he finally tendered his resignation to the Queen at 6.30pm the following Monday, March 4.
On the morning after the election, the Queen was advised that she would not be called upon to take action "unless and until" Mr Heath tendered his resignation. Meanwhile Mr Heath decided that he would open negotiations with the Liberals to see whether they would be able or prepared to form a coalition, or enter into an understanding to support a Conservative government.
In the days before mobile telephones, No 10 had difficulty reaching Mr Thorpe, celebrating his own victory in the West Country. He had been waiting by his phone, "but there was something wrong with it, and it had never rung".
When contact was finally established he agreed to come to London to talk to Mr Heath. Adopting cloak-and-dagger tactics to evade waiting journalists, he donned a country coat and wellington boots over his town suit, walked across three wet fields to a farm, where he was met by a car and driven to Taunton station.
Mr Thorpe was sympathetic, but failed to get the backing of his party for a deal.The Liberals demanded that the Conservatives commit themselves to electoral reform as the price of an arrangement. The most Mr Heath could offer was the commitment to a Speaker's Conference inquiry into the matter.
Lord Armstrong admits he was close to tears at the end of the tortuous negotiations, while Mr Heath confessed he felt worn out. Lord Armstrong went in the car with Mr Heath as he made his final journey to the Palace as Prime Minister.
"On the drive we neither of us said a word. There was so much, or nothing, left to say".
Gordon Brown must be dreading finding himself in the same gloomy situation.Reuse content