The by-election was caused by the death of the sitting Liberal MP, Sir Joseph Pease on 23 June 1903 at the age of 75.

Pease had been MP for Barnard Castle since the 1885 general election, and before that one of the two MPs for South Durham since 1865.

The Friendly Society of Iron Founders agreed to sponsor a Labour Representation Committee candidate.

Arthur Henderson was selected, receiving 5,619 votes from their membership, defeating Robert Morley, who took only 1,411.

He would serve three times as Leader of the Labour Party, and as both Home and Foreign Secretary, as well as winning by-elections in four other constituencies.