The 1945 Bournemouth by-election was held on 15 November 1945. The by-election was held due to the elevation to hereditary peerage of the incumbent Conservative MP, Sir Leonard Lyle. It was won by the Conservative candidate Brendan Bracken,^[1] who was a prominent supporter of Winston Churchill and Conservative parliamentarian who had lost his Paddington North seat to Labour in the 1945 Labour landslide. Somewhat unusually, there was a significant swing to the governing party, with Labour achieving a swing of more than 10%.

This election had the biggest swing for an incumbent governing party in a by-election until the 2021 Hartlepool by-election.^[2]