There is an academic expert on opinion polls whom I do not propose to name. That is because the minor controversy would go on for weeks. The expert in question is a specialist in predicting a parliament where no party has an absolute majority: a hung parliament, in the terminology that has developed since 1974, when Edward Heath failed to win.

This more modern expert invariably has recourse to the argument that there is a bias built into the electoral system in favour of the Labour Party. Even he, however, has come round to the possibility that Mr David Cameron may win the next election with a convincing majority.

Mr Nick Clegg, who is leader of the Liberal Democrats when Dr Vince Cable is otherwise engaged, has emerged as the only leader who wants to talk about a House of Commons in which no party has a majority. Even in his own party, the subject has gone in and out of fashion.

In the early days of the Social Democrats, when Roy Jenkins was still leader and before the 1983 election, commentators (myself included) would enquire earnestly what Her Majesty proposed to do if the new alliance with the Liberals succeeded in holding the balance. As we know, Margaret Thatcher won by a landslide. It was a great waste of time for all concerned.

With Mrs Thatcher securely in place, the speculation did not abate. On the contrary: during the 1987 campaign and before it, the press played a game with David Steel and David Owen. The game was for them each to say something slightly different about their relations with the other parties.

The papers would then report a "split" between the leaders of the Alliance. And Lord Owen, as he was to become, rarely let the papers down. He had a weakness for speaking as the spirit moved him and for not sticking to the script: he despised scripts. The consequence was that he would differ slightly not only from what Lord Steel had said, but also from what he himself had said on some previous occasion. Mrs Thatcher won confidently.

After 1988, when Paddy Ashdown become leader, he promulgated the doctrine of equivalent distance from both parties. But it was a very odd method of measuring distances. Within months of Mr Tony Blair's accession, Lord Ashdown was snuggling up to Mr Blair. We shall return to this interlude, but let us complete the story.

Mr Charles Kennedy possessed a justifiable suspicion of Mr Blair. Rejecting the advice of the Blairite commentators – then a more pervasive group than they are today – Mr Kennedy did not want to have too much to do with the new prime minister. Sir Menzies Campbell tried to do the same, but did not wholly succeed. From time to time he liked to say he was a "Radical" and so would incline more towards Labour: an inclination which is by no means inevitable in the modern world.

We return to the relationship between Lord Ashdown and Mr Blair. On Mr Blair's side, it was a flirtation; on Lord Ashdown's side, a romance. He might at last catch a glimpse of the alluring apparel of power; but, for Mr Blair, the Liberal Democrats might help prop up a majority which, before the 1997 election, was not yet secure. And so the Labour manifesto said: "We are committed to a referendum on the voting system for the House of Commons. An independent commission on voting systems will be appointed early to recommend a proportional alternative to the first-past-the-post system."

Alas, Mr Blair had no further need for the services of Lord Ashdown (who was to retire as leader of his party two years later). He had a huge majority already. Mr John Prescott, as honorary custodian of the cloth cap, might make trouble if any concessions were made to the hated Liberals.

In fact, the alternative vote – 1, 2, 3, ... with the bottom candidate or candidates dropping out – was proposed by Ramsay MacDonald's minority government in 1929. It would have been embodied in legislation if the financial crisis of 1931 had not supervened.

There is something else to be remembered. Enoch Powell used to be fond of remarking that one member in parliament represented one constituency, and that this had always been the case. But it had not always been so. People accepted what Powell said because they were intimidated by him. In the 19th and for much of the 20th century, many seats returned two members: one of the last was Preston in 1945.

In the 1997 government, the two leading proponents of the alternative vote were Robin Cook and Peter Mandelson. Mr Cook is, sadly, dead, while Lord Mandelson has quite enough on his plate with which to keep himself occupied.

In those faraway days, Lord Jenkins had a high regard for Mr Blair, while Mr Blair looked upon Lord Jenkins as one of the principal sages at his disposal. It is interesting that the manifesto specified "a proportional alternative" to the existing system. The explanation lies in old Liberal theology. The purists of proportional representation used to insist – probably carry on insisting – that the numbers voting should reflect mathematically the number of seats in the resultant assembly. Sometimes this does not happen when the alternative vote is used. There are even some bright sparks about the place who claim to have worked out that the alternative vote can be even less "fair" than first-past-the-post.

Lord Jenkins in his report supplemented the alternative vote with a propping-up system, the better to reflect proportionality. For myself, I have a horror of party lists supplied by the central committee and a suspicion of candidates who were runners-up but deemed successful in various special circumstances.

People take different views. Lord Jenkins worked quickly and industriously, with a wealth of apt illustration and happy metaphor. And, naturally, it was forgotten almost as soon as it was published.

There was a certain chilliness between Mr Blair and Lord Jenkins, at any rate on the part of the latter, and who can blame him? The moral is that great changes usually come about by accident. We still do not know whether Mr Jeremy Thorpe (who is still with us) was offered the post of home secretary in 1974 in a Tory cabinet. He, or his party, were certainly offered a Speaker's Conference on electoral reform as a reward for sustaining the Conservative government. The Liberals turned away with apparent scorn.

In 1964, when Harold Wilson had a tiny majority, he rejected any idea of cooperation with the Liberals. In 1977-78, when James Callaghan had lost his majority completely, he turned down any new proposals for the European Parliament.

The best chance for the Liberal Democrats came in 1997. Taking it would have had nothing to do with them. It would have been up to Mr Blair and to Mr Gordon Brown, if he had directed his mind to the subject at all. I wonder whether, with electoral reform by now safely on the statute book, he would not look forward, not to a catastrophic loss, but to a modestly hung parliament?