Increased turnout: good for keeping the Tories out?

What is the turnout today? There's been speculation that it may top 70%, which would represent a big leap from 61.4% last time around. Here are the figures for the last 5 general elections:

2005: 61.4%
2001: 59.4%
1997: 71.4%
1992: 77.7%
1987: 75.3%

The most interesting thing here is the gap between 1997 (Labour's landslide) and, on the other hand, the elections in 2001 and 2005. They illustrate the steep decline in enthusiasm and support for the Labour government. On both occasions Labour held on to substantial majorities despite greatly decreased votes compared with 1997.

It looks like the closeness and unpredictability of today's election has driven up turnout. It's possible the TV debates and postal voting are also factors at work here.

If so, I admit to being surprised. I'd initially predicted turnout would be similar to 5 years ago - I thought the factors encouraging higher turnout would be balanced by sheer disenchantment with the political class (especially after the MPs expenses crisis).

But we'll only know for certain when the results come in. And will the rumoured rise in turnout benefit the anti-Tory vote? It's possible that a desire to keep the Tories out is driving many people to the polls, but we can't be sure just yet.

Join me from 11pm for live-blogging on Election Night.