During 1975 Thorpe campaigned for electoral reform, citing the "Great Vote Robbery" of the year before. He argued that electoral reform on a proportional basis would bring about a centrist stability to British politics that would favour British business. In the June 1975 referendum on the UK's continuing membership of the EEC, Thorpe campaigned for a "yes" vote alongside the pro-Europeans of both major parties, appearing with Heath (recently replaced as Conservative leader by Margaret Thatcher) at the Oxford Union. The referendum resulted in a two-to-one approval of the UK's membership, but Thorpe failed to stem the decline in his party's electoral fortunes. In the Woolwich West by-election on 26 June 1975 the party lost more than two-thirds of its October 1974 vote, a "major humiliation" according to "The Guardian".