The Bournemouth West by-election was held on 18 February 1954. It was held due to the resignation of the incumbent Conservative MP, Robert Gascoyne-Cecil. It was won by the Conservative candidate, John Eden. When Eden was elected he was the youngest member of the House of Commons of the United Kingdom, known as Baby of the House.
References
Bournemouth West by-election, 1954 Wikipedia(Text) CC BY-SA