Of the many referendums promised in Labour's election manifesto, one is on the electoral system by which MPs are sent to the House of Commons.

Before the end of this parliament Tony Blair's government would offer voters a choice between the status quo and a proportional alternative.

But some alternatives are more proportional - and advantageous to different parties - than others. Deciding which one of them to put before the public is what the Jenkins Commission was set up to do.

The Independent Commission on the Voting System, to give it its full title, was established by the government last December and given 12 months to come up with an alternative to first-past-the-post for Westminster.

Terms of reference

Home Secretary Jack Straw set out the commission's terms of reference

The prime minister appointed the Liberal Democrat peer Lord Jenkins of Hillhead - at the time leader of the party's peers - to chair the commission.

The terms of reference he and his fellow commissioners were handed by Home Secretary Jack Straw - an implacable opponent of proportional representation - stated that whatever alternative electoral system they eventually recommended, it had to meet the following criteria:

• The requirement for broad proportionality

• The need for stable government

• An extension of voter choice

• The maintenance of the link between MPs and geographical constituencies.

The idea of setting up the commission was agreed between Labour and the Liberal Democrats before the election, when the two parties negotiated a joint agreement on constitutional reform.

Of course, this was also before the prime minister had any notion he would be forming a government with so large a Commons majority that whatever any other party at Westminster chose to do, it would in parliamentary terms be of supreme irrelevance.

Who are they?

Blair agreed to set up the commission before Labour won its biggest ever Commons majority

But Mr Blair still, as was widely predicted, chose Lord Jenkins - former home secretary and chancellor under Harold Wilson, president of the European Commission after that, and one of the "gang of four" who split from Labour to found the SDP in 1981 - to chair the commission.

He has been a public supporter of reforming how MPs are elected to Westminster since the 1970s.

The other four members are a peer each from Labour and the Tories, an ex-senior civil servant, and a political commentator.

Baroness Gould is best known from her days when, as plain Joyce Gould, she was Labour's director of organisation under Neil Kinnock and John Smith - in which capacity she played a prominent role in purging Militant from the party.

Joyce (now Baroness) Gould: Prominent in Labour's purge against Militant

She also sat on Labour's internal working party on electoral systems - chaired by Raymond (now Lord) Plant - that spent much of the early 1990s examining the subject. At the time, she came out in favour of a version of the alternative vote.

Tory peer Lord Alexander is a barrister and chairman of Nat West Bank. He authored a book - "Voice of the People" - that expressed a preference for the single transferable vote.

Sir John Chilcott is a former permanent secretary at the Northern Ireland Office. As a civil servant he was not permitted to express any public views on electoral reform, and was appointed to the commission immediately upon his retirement.

But he will have observed the single transferable vote in operation in Northern Ireland's local elections.

David Lipsey, onetime advisor to prime minister Jim Callaghan and now political editor of the Economist, is the final member.

In 1992 he wrote a Fabian pamphlet which strongly supported the alternative vote - a form of electoral reform which also tends to be favoured by first past the post supporters pushed to identify a single other system they could live with.

What about the ordinary voter?

Polls show support for PR - but excitement is a different matter

There was some criticism from the pro-reform camp when the commission membership was unveiled that it was too establishment-oriented.

The experience and instincts of a party apparatchik, a banking executive, a Whitehall mandarin and a Westminster-based political journalist did surely not provide the best antecedents for an outcome that would open up the political process to new, insufficiently represented voices?

Partly in order to meet such complaints, and also to demonstrate the commission's desire to incorporate "bottom-up" input from voters at the grassroots of politics into its deliberations, it hosted a series of open meetings in various cities.

They were not a massive success. The public turned up - but not in the large numbers hoped for, considering a change of crucial constitutional importance was being discussed.

The meetings were often held during working hours, limiting the potential attendance. Most people didn't even know they were being held at all, as the main publicity for them was an occasional advert in the local press.

The result was that while hardened troopers from the pro and anti-reform camps made sure they were there to put their practised views, "ordinary voters" were less well represented.

The truth is that although opinion poll after opinion poll has indicated public support for some kind of proportional representation, relatively few people get sufficiently hot under the collar over the issue to immerse themselves in the often complex technicalities that differentiate various electoral systems.

The Jenkins Commission, having studied those technical details at great length, has finally backed a version of the alternative vote.