2016 Sleaford and North Hykeham by-election

A by-election for the United Kingdom parliamentary constituency of Sleaford and North Hykeham was held on 8 December 2016. It was triggered by the resignation of incumbent Conservative Party Member of Parliament (MP) Stephen Phillips, who stood down citing irreconcilable differences with the Conservative government led by the Prime Minister Theresa May over Brexit—the British withdrawal from the European Union (EU). Conservative candidate Caroline Johnson won the by-election, comfortably holding the seat for the party with over half of the vote share.

Phillips had won a large majority of 39 per cent in 2015, with the Labour Party candidate coming second. The constituency had been held by the Conservatives since it was first contested in the 1997 general election and was considered a safe seat for the party. Sleaford and North Hykeham was estimated to have had a vote share of more than 60 per cent in favour of leaving the EU in the 2016 EU membership referendum and Brexit was a key issue in the by-election campaign. Phillips had supported a UK withdrawal from the EU but resigned in opposition to the government's handling of the issue – he felt that Parliament was not being consulted sufficiently.

Ten candidates stood in the by-election. The Eurosceptic UK Independence Party (UKIP) came second with 13 per cent of the vote, followed by the Liberal Democrats with 11 per cent of the vote and Labour on 10 per cent. The by-election result was widely seen as poor for the Labour Party, whose vote share decreased by 7 per cent.