Ken Ritchie: What's so special about "my" MP?

'The first-past-the-post [FPTP] voting system goes back to before time, almost." So said Richard Shepherd MP in the Commons in February. But it is not the case. There is nothing untouchable about our voting system, and when our forebears found reasons to change it, they did. We may have the "mother of parliaments", but her children have rejected her old ways.

One of the supposedly sacred aspects of our system is "the constituency link", i.e. the idea that each of us has a single, local MP to whom we go when we have a problem. Whether you voted for them or not, the relationship with "your" MP is meant to be an almost umbilical link. But we managed without single-member constituencies nearly 750 years ago, so surely we can summon the courage to do so now by moving to a more representative arrangement?

When, in 1265, Simon de Montfort decided that his parliament should be elected, he asked for two representatives from each county and selected boroughs. These were elections without parties, opinion polls and leaders' debates, and with few voters. Multi-member constituencies were the norm until 1885. Paradoxically, although the Conservatives are now most firmly opposed to the multi-member constituencies that proportional representation (PR) requires, it was the Tories, joined by many Liberals, who resisted getting rid of them. Some two-member constituencies survived until 1950.

It was around the middle of the 19th century that democracy started to change significantly. The Chartists' agitation and Reform Acts began the slow work of building a mass franchise, and shows of hands were replaced by polling booths and ballot boxes. But what 21st-century politicians cannot understand was already clear to 19th- century analysts: FPTP doesn't work.

Thomas Hare, the great 19th-century political scientist, observed that the system was debasing politics, providing scope for "the lower motives" of politicians. He also noted that "nearly half of the electors are, for all useful purposes, in the same position as if they were disenfranchised", which may ring a bell with voters of today.

There were complaints that parties with the most votes did not necessarily win – something we may well see this week – and, as in our local elections, parties could sweep the board without the votes to justify it. In 1867, there was a first modest trial of PR: constituencies that returned three members moved from FPTP to the "limited vote", which gave electors only two votes, a change that gave more chance to minor parties. But politicians then, as now, were fearful of more radical reform. In 1917, the Commons rejected PR by eight votes, but agreed the use of the single transferable vote (STV) for the 1920 Irish elections and for the university seats that were not abolished until 1950.

Now the old two-party dualism is dead, but the electoral system and the two biggest parties won't admit it. Despite promising a referendum on how we elect MPs, Labour's huge majority in 1997 made its appetite for reform vanish. Nonetheless, we now have PR for electing our members for the European, Scottish, Welsh, Northern Irish and London assemblies. In 2007, Scotland joined Northern Ireland in using STV for its local elections.

To suggest that FPTP with its single-member constituencies is part of our national heritage is absurd. On Thursday, it will produce another very silly result. Let's change it.

Ken Ritchie is the chief executive of the Electoral Reform Society