Dr David Butler, the grand old man of British psephology, was on to something when he observed on BBC News this lunchtime that he thought electoral reform would come about only if two general elections in a row resulted in a hung parliament.
We've just had one -- two in a row would take high odds -- and some will say that Nick Clegg will have failed completely if his party's new-found presence on the national stage does not result the Lib Dems securing some form of proportional representation.
But the third party has a history of being far more ambiguous about PR than is generally thought. It has not always been the glittering prize the BBC's political editor, Nick Robinson, suggested it was this afternoon. When asked by his colleague William Douglas Home what he should emphasise in a by-election campaign in 1957, for instance, the then Liberal leader, Jo Grimond, replied: "Proportional representation. Wouldn't it be awful if we ever got it?"
A week before the general election of 1964, Grimond sensed that Harold Wilson was heading for, at best, a very slim majority (it turned out to be four). But using any bargaining power he might have to extract a Liberal-friendly electoral system was not on Grimond's mind.
As Michael McManus puts it in his biography of the Liberal leader, Towards the Sound of Gunfire:
He said that, in the event of a hung parliament, "it would not be our object to make political capital . . . We would not expect a government to bring in proportional representation . . . we would try to press policies which certainly we want enacted, but which we also think would be particularly relevant and command wide support in the country."
And the day after the election, "Grimond again preferred caution to threats: 'Some time we shall have to change the electoral system . . . not immediately . . . the most important thing to face is the economic situation.' "