10 million people in the UK entitled to vote aren't even on the electoral register

http://www.progressonline.org.uk/2015/09/23/1-9m-people-are-about-to-lose-their-vote/

10 million, that more than voted for the Labour Party at the last general election.

I have often thought that perhaps parliament should have empty seats to represent the people who didn't vote. 

Unfortunately, (or fortunately)  at the last general election 30,691,680 people voted, 66.1% of those registered to vote, that means that something like 15,740,513 people didn't vote, add to them the estimated 8 million not even registered to vote and that's a massive 23.7 million people who could have voted but didn't.