The Prime Minister must honour his promises and reform the House of Lords

The Prime Minister, we report today, is facing a full-blown Cabinet revolt over House of Lords reform - and not before time. Mr Blair and his government have had the best part of four years to meet their manifesto commitment to make the Lords "more representative and democratic" and, although the majority of hereditary peers no longer sit in the Lords as of right, the reform is far from complete. Worse almost than its incompleteness, however, is the impression - which Mr Blair has done nothing to dispel - that the Government has either lost the will to complete it or cannot decide how to proceed.

The Prime Minister, we report today, is facing a full-blown Cabinet revolt over House of Lords reform - and not before time. Mr Blair and his government have had the best part of four years to meet their manifesto commitment to make the Lords "more representative and democratic" and, although the majority of hereditary peers no longer sit in the Lords as of right, the reform is far from complete. Worse almost than its incompleteness, however, is the impression - which Mr Blair has done nothing to dispel - that the Government has either lost the will to complete it or cannot decide how to proceed.

What apparently triggered the revolt was concern among some senior ministers that, while time was running out for further reform in this Parliament, there was not the slightest hint that the manifesto for the next election would refer to Lords reform at all. In the meantime, Mr Blair had restated his preference for a second chamber that was fully appointed, rather than one that was wholly or partially elected. This was the last thing these ministers - and many MPs - wanted to hear.

The option of an all-appointed second chamber has already shown itself to be one of the least acceptable of all. In Parliament, it was rejected overwhelmingly in the vote on Lords reform 18 months ago and there is no sign that the mood of MPs has changed. In the country at large it could prove an electoral liability, reminding voters of the generous patronage exercised by Mr Blair, widely known as "Tony's cronyism". The undertaking reportedly given by Mr Blair recently, to limit the number of Labour peers he nominates personally was hardly reassuring in this respect.

The reform option that MPs came closest to endorsing - it failed by only three votes - was for a hybrid system under which 80 per cent of the second chamber would be directly elected, leaving 20 per cent to be appointed by an independent commission. Some combination of election and appointment - with the majority elected - has much to recommend it. The potential for the prime minister or government of the day to fill seats by patronage would be severely curtailed, yet a quotient of appointed "lords" would allow interesting and engaging mavericks to make a contribution to the country's political life.

The preponderance of elected "lords" would give the electorate a considerable say - and so a stake - in the composition of the Upper House. At the same time, the fact that not all members were elected would keep the distinction between the two chambers, in representational authority. There is also an argument for having elections to the second chamber conducted on principles that vary from those that apply to the House of Commons. The length of an elected term could be longer, for instance, so that elections dates did not coincide, or there could be a system of proportional representation, as in the European elections.

Whichever scheme was chosen, it would certainly be an improvement, not only on the outdated, undemocratic system the House of Lords used to embody, but on the unsatisfactory half-way house we have at present. Now it has started, reform of the Lords cannot be allowed to stall. As it currently stands, this major constitutional reform exemplifies Mr Blair's reforming zeal at its least impressive. As with his efforts - not unrelated - to reform the judicial system and create a Supreme Court, he has tackled the Lords reform with little apparent appreciation of the whole. Our country may be unusual in not having a written constitution, but this does not mean that branches of the system can be tweaked piecemeal and at will. There needs to be consistency and coherence.

Reform of the House of Lords began as a project that was popular - except among those whom it stood to displace - and long overdue. Any hope Tony Blair might have to leave a reputation as a modernising politician will be compromised unless he completes it. In this particular Cabinet revolt, we have no hesitation about taking the side of the rebels.