From my findings below I reckon the votes cast by the 18 - 24 age group amounted to barely 6% of the total vote cast. So for every young voter who turned out there were four pensioners who turned out to vote.
We've all seen the standard Eu voting demographic which looks like this:
This is from a quite detailed set of statistics surrounding the referendum by Lord Ashcroft.
The full Lord Ashcroft data is (HERE) and the BBC version is (HERE).
Both though miss one very important (or vital) statistic. What was the turnout demographic?
Look as you might, there is very little about how many people by each age group voted rather than just which way they cast their vote.
There is this from The Financial Times (HERE) that shows a trend that the older a towns population, the higher the Brexit vote. But while it is qualitatively interesting it gives no real indication of how many people from each age band voted.
But there was one source based on a poll and reported by Sky data on Twitter. Polls, as you know are far from definitive but I think it would be fair to say that it could be regarded as reliable to +/- 5%.
Here is the tweet.
(The caveat that was here relating to the Sky Data has been removed as it proved to be a red herring)
From this we can see that while 73% 18-24 year olds voted to remain, only 36% of that age band in total actually turned up to vote. The turn out for this age band was dismal.
In order to translate this into an approximate number of voters, we need to know the population density within that age group.
Here is a demographic table for the UK from Wikipedia (HERE)
We get (approximately)
18 - 24 5,900,000
25 - 34 8,400,000
35 - 44 8,800,000
45 - 54 8,700,000
55 - 64 7,400,000
65+ 10,500,000
Clearly, not only is the 18-25 age group the least likely to vote but they are also (by far) the smallest group of voters.
If you now use the the Sky data you can get a rough idea of how many people voted in total from each age band
18 - 24 (5,900,000 * 0.36) 2,125,000
25 - 34 (8,400,000 * 0.58) 4,875,000
35 - 44 (8,800,000 * 0.72) 6,335,000
45 - 54 (8,700,000 * 0.75) 6,525,000
55 - 64 (7,400,000 * 0.81) 5,995,000
65+ (10,500,000 * 0.83) 8,715,000
This above table totals to 34,570,000 whereas the actual total who voted was 33,577,342 which is less than 3% different (2.95%)
I would suggest that within a 5% tolerance the figures above are fairly good.
So from this we can see that for every young vote there were four pensioner votes. The young vote (18- 24) was only 6% of the total vote cast.
If the young had voted with the same dedication as anyone above the age of 35 then the vote would have been with remain.
