As the public debate over Britain’s electoral system reaches fever-pitch, YouGov has published a projection estimating the composition of Parliament if an election were held today under the alternative vote system. If the projection is correct, the big winners would be the Liberal Democrats who would secure 19 more seats under AV than under the first past the post system.
The BBC has a section on its website which estimates the outcome of past elections had AV been in place rather than first past the post. Once again, the Liberal Democrats are consistent winners, but changing the voting system would not have changed the outcome of these contests, with the Conservative and Labour parties still securing outright majorities in Parliament.
Both of these projections should be treated with some caution. The actual impact of AV will depend on local constituency circumstances, and the second preferences of supporters of minority parties such as UKIP or the Greens.