To tactical vote, or not to tactical vote, that is the question.

On his retirement as Liberal Leader David Steel talked of the part luck had played in his career. As a young MP he had won a high place in the ballot for private members' bills, and his subsequent Abortion Act made him nationally known. That was good luck.

Then in 1983 the Liberal/Social Democrat Alliance almost, but not quite, pushed Labour into third place. With over 13 million votes there was no doubt that Mrs Thatcher and the Conservatives were the winners, but the Alliance's 7 781 000 were very close to Labour's 8 457 000. That, said Steel, was bad luck. Had the two figures been reversed than the indignation produced by the gross unfairness of the result (Labour took 209 seats against the Alliance's paltry 23) would not have evaporated so quickly, and a reform of the voting system would have been irresistible. Politics could have been transformed a quarter of a century ago.

The question many Liberal Democrat supporters must decide in this election is whether to vote tactically to keep out the Tories, adamantly opposed to any sort of electoral reform, or to remain true to their principles and vote Liberal Democrat. I believe the later course is the right one. The three major parties are so close that, whoever wins, in terms of either seats or votes, will have no democratic legitimacy to form a government alone. If the Liberal Democrats can push either of the other parties into third place then, this time, the case for real proportional representation, using STV rather than the unproportional AV, really will be irresistible.

So every Liberal Democrat vote is vital, whether or not it results in the election of an MP.