Why it's so hard to predict the result of the general election

The Tactical Voting Blog: The polls can only tell us so much

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One ugly fact about elections in the UK is that they are decided in just a small number of the country's 650 seats.

Parties don't even have to be that close for it to matter far less how many votes you get than where you get them.

Anti-Brexit campaign group Best for Britain has some new data to illustrate this - and the importance of tactical voting.

They've calculated that as few as 40,704 tactical votes - moved between Final Say supporting parties - could prevent a Tory majority.

That's smaller than any single parliamentary consistency (the smallest of those is Wirral West, which has just over 55,000 people - the largest has 110,000 - the Isle of Wight).

That's because if the votes are in the right place they swing seats, whereas if they pile up in safe seats nothing happens - there is no effect on the election result.

They also think the Tory majority has halved from 82 to 40 seats since the end of November - thanks to shifts in the polls.

They recommend tactical voting in 36 marginal seats to swing the result - they each need fewer than 2,500 to take a seat off the Tories.

Supporters of a final say will wish them luck. If it were easy to mobilise voters like this, the election would be a foregone conclusion - but it's not. But what this illustrates above all is that we don't know what's going to happen on Thursday.

It's not possible to meaningfully tell whether such a small number of people spread across the country are going to turn out in the right places - that will make the difference between a majority and a hung parliament. In that respect the election will be decided on a pin-head and polls can only tell us so much.