Political coverage and blogging in the UK has a rather odd love-hate relationship with electoral numbers. On the one hand, the latest opinion poll figures get reported, re-reported and mis-reported at length, with the mere fact that a change in ratings is well within the margin of error not being reason enough to stop a cavalcade of comment.

Yet despite this love of talking electoral numbers, those that are talked about come from a fairly narrow range of sources.

So here instead are three other numbers – all simple in concept, but interesting in implication.

First, since 1970 49% of Parliamentary seats have not changed hands at any of the general elections which have taken place. For half of the country’s constituencies (or their predecessors), all the general elections since 1970 have produced no change – not even the once – in the local result.

Landslides have come and gone, the internet has arrived and the Berlin Wall has departed, Thatcher and Blair have swept all before them and then been brushed aside themselves. All through that period, in half the country the same party has won the constituency at every single election.

So whatever dramas the overall general election campaign will bring in 2010, for much of the country it will actually be a case of the same again as it has been at every election over the last forty years. Swinging back and forth to choose the government is something other people do.

Second, although the national media will understandably focus on the Cameron versus Brown, Conservative versus Labour contest, again if you look at the constituency level you find a different story.

Only a minority of constituencies are Labour-Conservative battles. A majority – by just a whisker, but still a majority – of constituencies have one of the other parties in first or second place, or are three way marginals (taking the Thrasher and Rallings list of three way marginals, which is in fact slightly cautious in its classification).

Whilst the national media story may be about Conservative versus Labour, when it comes to actually choosing how to vote on the constituency ballot paper, half the country will be facing a different choice.

Thirdly, there’s another statistic featuring a half. Over the last few general elections, research has shown that on average only around half the people who voted Liberal Democrat (or one of its predecessors) at one general election also voted Liberal Democrat at the next. That churn is a huge challenge for the Liberal Democrats, but also holds out a big opportunity – for it means there is a large pool of people who have voted for the party but aren’t currently intending to do so.

Whatever else the 2010 general election may bring, it’ll be an election of three halves.