Twenty years from now, if all goes to plan, our children will be teasing us. They will return from history classes at school, or they will look up from documentary programmes on television - assuming that such things still exist - and they will talk with mocking disbelief about the House of Lords. "Were you really alive," they will ask, "at a time when aristocrats were able to vote in Parliament, and for no better reason than that they had inherited their titles?". And we will be obliged to answer that yes, incredible as it may seem, we have that much in common with the good people of, say, the Tudor age. Of all the anachronisms of Britain in the 1990s, none is more ludicrous than the spectacle of 10th Dukes and 15th Earls queuing in the lobbies to cast their votes on the great issues of the day. Their ancestors may have been men of the utmost distinction (although often they were not), but it should be unnecessary to say, more than two centuries after the American and French revolutions, that this hardly entitles them to a special influence over public affairs. No other democracy in the world operates in this way, and these archaic constitutional arrangements show Britain at its weakest - a living heritage park where the medieval nobility are not mere waxworks but still living, breathing points of political reference.

Labour has promised to put an end to this if it wins the next election. As a first step towards reform, it will introduce a short Bill stripping those peers who have inherited their titles of their seats in the Lords. Lord Irvine of Lairg, who is likely to be Labour's Lord Chancellor, said in an interview in the New Statesman last week: "The time for abolition of the hereditaries has come." He believes that the dukes, earls and viscounts know the game is up and will go quietly, but this seems optimistic. They have not defied history for this long by meekly accepting the inevitable and, sure enough, last week we saw signs of resistance. Lord Cranborne, Leader of the House of Lords and heir to the sixth Marquess of Salisbury, put forward the case for the hereditary peerage in a speech to the Conservative think-tank Politeia. We are likely to hear more of it.

Labour's proposals, Lord Cranborne argued, would steal power from the elected chamber and create the greatest quango in the land. Further, they would destroy something that is good. Lord Cranborne said: "It is helpful to the body politic for Parliament to contain a body of amateur politicians. The only such body we now have is the hereditary peerage and it is a body chosen by lot. The inventors of democracy - the Athenians - would say that was the fairest system of all." The hereditary peers, he goes on, "owe no favours to patronage. They are not paid". It is hard to imagine a feebler argument. These are just ordinary blokes, it seems, with no vested interests and no debt to anybody, like the 12 good men and true in the jury. Well, no. They were not chosen by lot; they have not just walked in off the street and they owe plenty of favours, some of them going back a very long way. The idea that the hereditary peers help to give us a moderating chamber of informed amateurs whose views and experience reflect those of the country at large is nonsense, and insulting nonsense at that.

Lord Cranborne went on to challenge Labour claims about the voting behaviour of the hereditary peers, suggesting that they are less Tory in practice than most of us assume, and that they have played a less decisive constitutional role than Labour has suggested. This argument misses the point. It would make no difference if every single hereditary peer subscribed unquestioningly to the New Labour programme. It would make no difference if they had never once exerted a decisive influence on legislation. It would make no difference if they never voted in the Lords. Lord Cranborne - and Labour as well - should see that the reason we must abolish the hereditary right to vote in the Lords is that it belongs to the age before democracy. It is privilege without merit; it is power, however slight or notional, without responsibility. In the 1990s you do not need to be a Leveller to believe such things are wrong.

The Labour Party has a bold constitutional programme for its first term, but challenged on such issues as Scottish devolution, proportional representation and freedom of information it has shown itself to be wobbly. Let us hope that on this issue it stands firm.