The road to the reform of the House of Lords has never been straightforward. Four years ago, the Commons was presented with seven options for reform and it declined to endorse any of them. On Wednesday evening, a similar menu was presented to it and, first, a chamber that was 80 per cent elected and 20 per cent appointed was accepted by a margin of 38 votes and then, rather more surprisingly, an entirely elected chamber was embraced by an even larger majority. It falls to Jack Straw, the Leader of the Commons, to decide how to proceed from here.

Analysis of the voting figures indicates that the wholly elected Upper House emerged because of some shameless parliamentary activities. Certain MPs who had supported a completely appointed second chamber and who had indicated their disdain for any elected element switched sides to back the exclusively elected suggestion. Mr Straw is wily enough to appreciate that this was a wrecking manoeuvre. If the Government were to come back with a White Paper that favoured a House which was totally elected it would soon find itself in the political quicksand. The 80-20 path is the one that he should follow (now that 50-50 seems to be highly unlikely) and as it was backed by Gordon Brown, David Cameron and Sir Menzies Campbell, there is the real prospect that, in time, it could indeed become law.

Mr Straw will, though, need to revise other aspects of his proposals for that to happen. He has to look again at the powers of the second chamber, its size and the electoral system.

If as much as 80 per cent of a new chamber is elected, there is far more danger that it will be emboldened to challenge the Commons with legislative deadlock as a consequence. The precise powers of the Senate, or whatever it is named, have to be specified with care. An Upper House should not be the House of Commons Mark II, but a body which concentrates on the constructive scrutiny not only of legislation within Whitehall but the torrent of initiatives from Brussels. It has to be a house of correction rather than of conflict.

An unduly large House would not be suited to detailed inspection of parliamentary measures. The current Lords, with a membership of 750 people, is one of the biggest second chambers in the world. Mr Straw originally favoured cutting it back to 540 but that was on the assumption that half the members would be appointed. It would be strange to have 650-odd elected MPs and 430 or so elected senators — a total of elected figures in excess of a thousand — in Westminster. The size of any new chamber, elected and appointed, should not involve more than 300 souls.

They should also be independent spirits. The party list notion put forward in Mr Straw’s White Paper was never attractive but appears abhorrent in the context of a mostly elected chamber. The voters should be asked to choose between candidates, not have a handpicked list of hacks imposed on them. The idea of a long yet nonrenewable term of ten or fifteen years makes sense, but it would be better for the chamber to emerge via the single transferable vote (as deployed in the Australian Senate and the Northern Ireland Assembly ballot this week), based on the counties.

Mr Straw has, nevertheless, an extraordinary opportunity ahead of him. A final settlement for the Upper House has been sought for almost a century. Before the centenary of the Parliament Act of 1911 is celebrated, it should finally be possible to make peace with the past.