Tomorrow's referendum will be decided, as all elections are, by those who actually turn out and vote.
We've not had a UK-wide referendum for 36 years when turnout was 64%. However, more recently, at the referendum on whether or not to have a elected mayor, 34% of Londoners bothered to vote. In the 1997 devolution referenda 60% of the Scottish electorate and half of the Welsh voted. Expectations for nationwide turnout are around 30%, however due to elections to the Scottish Parliament and Welsh Assembly as well as local elections in some English regions, it is likely to be skewed higher in these areas – with a potentially significant impact on the final results, especially as Scotland and Wales are already used to using other electoral systems.
However, the most important thing is not how many people vote, but who votes. Traditionally it is older people, often from higher social grades that are more likely to make it to the polling station. Conversely the youngest members of the electorate are least likely to turn out. Indeed, the polls are showing that older people, those in higher social grades and Conservative supporters are giving “No” the lead and pertinently they are also those most likely to tell the pollsters that they will actually vote.
This has significant implications for both the “Yes” and “No” camps. Much as at the 2010 General Election the lower the turnout the better the result would have been for the Conservative Party, the “No” campaign is likely to benefit from fewer people turning out while the “Yes” campaign stands a better chance of winning if turnout is high.
One thing that should also be considered is the psychology of voting. Is it easier, more motivating to make the effort to go and vote if you are voting for a change rather than voting to keep the status quo?