In 1974, as a newly elected MP for Southampton Test in the British Parliament, I was interrupted mid-speech by a Liberal from the benches opposite. "How can you claim to speak for the people of Southampton," he demanded "when you got only 39 per cent of the vote?"
"Who would you replace me with?" I rejoined. "With the Liberal candidate, who got only 23 per cent?"
That summed up for me a powerful advantage of the First Past the Post voting system. If the purpose of a general election is to send a representative for each community to Parliament (and a House of "Commons" is historically a house of "communities"), it is hard to go past the candidate to whom that community gave more votes than any other.
The other great virtue of First Past the Post is that it almost always produces a clear-cut winner. This is valuable in itself, but it also has a couple of further advantages. It means that the voters themselves - rather than deals done by the politicians after the votes are counted - decide the result. And the voters have that greatest of all powers in a democracy - the ability to throw out one government and to replace it with an identifiable and alternative government-in-waiting.
These virtues of certainty and predictability could be contrasted with the confusion and uncertainty that so often followed general elections in countries that used proportional representation systems. It seemed often that the voters played only a bit part and that the real decisions were left to the manoeuvrings of the politicians after the election.
In some countries, this meant that - however often the voters were asked - the outcome did not change. Post-war Italy, for example, had a record number of general elections, but the voters could never get rid of the Christian Democrats who simply came up with differing combinations of themselves and minor parties.
In other countries - and Israel was for a time a prime example - the results were completely arbitrary, with small, extreme parties often deciding who should form the government.
For all these reasons, I remained committed while in Britain to the traditional First Past the Post system. Indeed, I once sat on a commission that was asked to recommend any changes that might be needed to the British electoral system. I confess that I was instrumental in ensuring that the commission made no such recommendation.
And I recall that, at the time of the 1993 New Zealand referendum on MMP, and while I was still in the UK, I was telephoned by the organisers of the anti-MMP campaign and asked for advice and a statement of support for their position. I would have voted against MMP in that referendum.
Eighteen years later, I am older and, I hope, wiser.
My reasons for seeing virtue in First Past the Post seem to me still to be valid, and my concerns about the dangers of proportional representation still carry weight.
But my experience of MMP has given me a greater appreciation of how its advantages stack up against the downsides of First Past the Post. And what I now understand is that no system is ideal. Each has its strengths and weaknesses, and delivers its own particular benefits and drawbacks. In the forthcoming referendum, the question is not so much which system is "best" but rather, what do you want your system to deliver?
MMP supporters have always promised that it will result in a fairer and more representative parliament and a more effective voice for otherwise unrepresented minorities. That promise has largely been delivered. And MMP has also put an end to what Quintin Hogg famously called the "elective dictatorship" - the power of a party with a parliamentary majority (even if it obtained only a minority of the total votes) to do whatever it wants without regard to anyone else.
Under MMP, major government parties have been forced to take a more inclusive and conciliatory approach to other views and interests. They have seen the need to negotiate for support before introducing legislation, rather than relying on a parliamentary majority to ram it through - and that has meant, on the whole, better legislation and a more constructive parliament.
But the main surprise is that, even with these advantages, MMP has not denied us a fairly straightforward choice between broadly right-of-centre and left-of-centre governments. We get, in other words, the best of both worlds - we have made the promised gains in the sense of a more equitable representation without sacrificing our ability to choose between readily identifiable options as to who should form the government. And we still have that essential power to throw one government out and replace it with another.
This is not to say that MMP should be uncritically supported. No one watching the machinations in Epsom, for example, could say that change is not needed. I, for one, remain unhappy at the power exercised by party machines in deciding who should get into Parliament through the party lists. And we need to watch carefully that fringe parties do not gain disproportionate influence over what our governments do.
But, in deciding which way to vote in the forthcoming referendum, we can at least applaud the genius of New Zealand voters who have ensured that, without achieving anything like perfection, we have at least created a system that works pretty well.