Campaigners have slammed Britain’s First Past the Post voting system after analysis revealed that proposed changes to constituency boundaries will hand the Conservative Party a crushing advantage in general elections.

The analysis – conducted by Electoral Calculus and – finds that the Conservatives would win 40 more seats than Labour if the two parties received exactly the same share of the vote, under proposed boundaries due to be introduced later this year.

The projections, based on recent polling, finds that if both parties received 38% of the vote, the Conservatives would win 285 seats (43%), while Labour would win just 245 seats (38%). The Liberal Democrats were projected to win 14 seats (2%) with 10% of the vote.

Mike Smithson, who carried out the analysis, said, “the gains for the blue team are so great and provide a very comfortable cushion against the prospect of a Labour victory.”

Labour’s front bench team have opposed the proposed boundary changes on the grounds that they are based on out of date voter data and “fails to include up to two million electors”. However, the party does not formally support the principle that the share of seats a party wins should match the share of the vote it receives.

Joe Sousek, a spokesperson for Make Votes Matter said, “Anyone can see that these findings are grossly unfair, because the number of seats each party wins has little relation to the number of votes they receive. Our First Past the Post voting system means elections are decided by how lines are drawn on a map – not by how the people vote. It’s time the UK adopted Proportional Representation so seats match votes and all votes matter equally.”