Data compiled by the Electoral Reform Society (ERS) for the Observer showed Ukip had received 3.86m votes for the one MP it had elected to the Commons. This compared with an average of 26,000 votes for every SNP MP, 34,000 for every Conservative, 40,000 for every Labour MP and 299,000 for every Liberal Democrat.

The ERS said that 24.2% of seats in parliament were now held by MPs who would not be there if a proportional voting system were in place. The previous record highest figure was 23% in 1983, when the former SDP suffered from first-past-the-post.