The longest continuously serving Member of the House of Commons in the United Kingdom is customarily designated Father of the House. The most important duty of the Father of the House is to preside over the election of a new speaker should that office be vacant at the beginning of a Parliament. However, a minister of the Crown is prohibited from presiding at the election of a speaker in the House of Commons; therefore, a minister is never considered the Father of the House, even if that minister is more senior than any other member.

The current Father of the House of Commons is Tam Dalyell (Labour Party), who was first elected for the seat of West Lothian (since renamed Linlithgow) in a by-election in June 1962. If two MPs have equal lengths of service, then whoever is sworn in first is counted as Father.

See also List of longest-serving members of the Australian House of Representatives

Fathers of the House