* The European elections don't use strict proportional representation, but rather an algorithm called the D'Hondt method - a process employing highest averages to allocate seats from party lists. It works by giving the first seat to the party with the most votes, then dividing their vote by 2 and looking at the list again. Whoever's top of the list now gains the second seat, then has their vote divided, and so on until all the seats have been allocated. Votes are always divided by "the number of seats you currently have plus one", so get smaller as the process continues.
The D'Hondt method churns out an end result that's roughly proportional to the number of votes cast without over-rewarding a landslide or under-representing minor parties. It's not perfect, but it does the job. If you're interested, here's an online calculator which allows you to play around with various voting combinations. I've had a go and discovered that in a seat like London it's pretty much impossible to gain an MEP on less than 9% of the vote. In constituencies with fewer than eight seats, even double figures can earn you nothing.
If you'd like a worked-through example, here's how the D'Hondt method was used to determine London's MEPs in the 2014 election.
In 2014 the votes cast in London were as follows.
Labour 806,959 (37%)
Conservative 495,639 (23%)
UKIP 371,133 (17%)
Green 196,419 (9%)
Lib Dem 148,013 (7%)
Others 8%
Labour took the first seat, after which their vote was halved (to 403,479) so the Conservatives now headed the list. They took the second seat after which their vote was halved (to 247,819). The list now looked like this.
Labour '403,479'❁
UKIP 371,133
Conservative '247,819'❁
Green 196,419
Lib Dem 148,013
Labour took the third seat, demonstrating how far ahead they were in the original poll, after which their initial vote was divided by three (to 268,986). UKIP now topped the list, so took the fourth seat, after which their vote was halved (to 185,566). The list now looked like this.
Labour '268,986'❁ ❁
Conservative '247,819'❁
Green 196,419
UKIP '185,566'❁
Lib Dem 148,013
Labour took the fifth seat, their third, after which their initial vote was divided by four (to 201,739). The Conservatives took the sixth seat, their second, after which their initial vote was divided by three (to 165,213). The list now looked like this.
Labour '201,739'❁ ❁ ❁
Green 196,419
UKIP '185,566'❁
Conservative '165,213'❁ ❁
Lib Dem 148,013
Labour took the seventh seat, their fourth, after which their initial vote was divided by five (to 161,391). The Greens then took the eighth and final seat, at which point all the arithmetical jiggerypokery ceased. If there had been a ninth seat UKIP would have taken it, and the Lib Dems would have had to wait until seat number twelve so earned absolutely nothing. End result as follows.
