14 Million people did not vote in 2017

There were 46.8 million registered voters for the 2017 election. 13.7 million in total voted Conservative, 12.9 million voted Labour and 5.6 million voted for other parties. But 14.6 million people who were eligible and registered to vote did not vote at all - considerably more than the number who voted either Conservative or for any other party...

The most significant finding about voter turnout in the 2017 election is that, with the exception of Scotland, constituencies with the highest turnout (i.e. fewer non-voters) were traditionally Tory strongholds, while the constituencies with the lowest turnout were traditional Labour strongholds. Does this mean that Labour only does well when voter turnout is low? Or does it mean that Labour might do much better in other constituencies if the turnout was higher in those places?

If we compare voter turnout in 2017 with voter turnout in, say, 1997, when Labour did exceptionally well at the polls, it is clear that many of the constituencies which Labour has 'lost' since then are among those with lower than average turnout. In other words, it is more likely that Labour voters have stopped voting than that they have 'switched' to voting Tory or LibDem (or even UKIP). It only takes a few thousand Labour voters to not vote, or even a few hundred in some cases, for the Tories to suddenly have a majority in that constituency.

The combination of more Tories voting and fewer Labour people voting may well have cost Labour that election...