The result of a British referendum on its electoral system shows how remarkable it was that New Zealand adopted MMP - and how much referendums are influenced by the mood of the moment. British voters have chosen to retain first past the post by 68 per cent to 32 per cent for a proposal called the Alternative Vote.

The result is devastating for electoral reform in Britain, burying the subject for another generation in the view of most commentators, and immediately devastating for Britain's third party, the Liberal Democrats. The referendum was their main purpose in joining a coalition with the Conservatives.

Over the past year the Liberal Democrats have had to reverse their pre-election positions on several issues and disappoint their supporters on many others as the Coalition has grappled with Labour's legacy of public spending. The party and its once-celebrated leader, Nick Clegg, have become so unpopular the party is now in a bind. It is unlikely to pull out of the Coalition and precipitate a new election. It would fare as badly as it did in the local elections held in conjunction with the referendum, where it lost half its seats.

The arguments for electoral reform were familiar to New Zealanders. A two-party choice no longer satisfies nearly all voters as it did a generation ago. Up to 25 per cent of voters are supporting other parties, but the system is not translating their votes into the same proportion of seats in Parliament.

Nearly all Conservative and most Labour MPs campaigned for the status quo, though Labour's new leader, Ed Miliband, supported change. The case for reform was led by the parties that stood to gain from it, as it was in New Zealand. The difference was that in this country those parties were not already in government. The result might have been different if they were.

Small parties sharing power in New Zealand have not fared much better than Britain's Liberal Democrats. New Zealand First came to grief in the first MMP coalition, the Alliance in the next, Act and the Maori Party are both under strain now. Act has dumped its leader and put its hopes of survival in someone outside the Government. The Maori Party has split over the compromises it has made.

Experience with MMP suggests voters for third parties are not interested in proportionate power, they want their vote represented in Parliament, not necessarily in the Government. Increasingly, the small parties have kept their distance from the governing party they support, preferring confidence and supply commitments to a formal coalition.

All five elections under MMP have produced government by the party that was first past the post. Proportional representation has changed less than its advocates hoped or its opponents feared. Minority governments still rule, tails have not wagged dogs, stability remains. The previous Government lasted nine years; polls suggest most voters want the present Government to have a second term.

Voters at this year's election will also have a referendum on whether to retain MMP. Polls show that most will vote yes. But the result, as in Britain, could yet be influenced by the third parties. If Act's gamble on Don Brash does not pay off, or the Maori seats return to Labour courtesy of Hone Harawira, the Government's return could be in doubt.

MMP is working well and could be better with some refinements. If it fails this year, it will be given a second chance against the preferred alternative. It deserves to survive - but voters are not theorists on electoral fairness, they want the system that produces the Government they want.