The 2015 General Election resulted in a net loss of seats throughout Great Britain, with Labour representation falling to 232 seats in the House of Commons. The Party lost 40 of its 41 seats in Scotland in the face of record breaking swings to the Scottish National Party. The scale of the decline in Labour's support was much greater than what had occurred at the 2011 elections for the Scottish parliament. Though Labour gained more than 20 seats in England and Wales, mostly from the Liberal Democrats but also from the Conservative Party, it lost more seats to Conservative challengers, including that of Ed Balls, for net losses overall.

Who was one of the Liberal Democrat challengers?