With the collapse in the Liberal Party and the increase in the Labour vote (December 1910 - 7.1% to December 1918 22.2%, - helped by the extension of the franchise to all men over 21 and all women over 30) - Labour became one of the most important parties at Westminster. It was only in 1920 that the first "Labour Peer" was recognised. The 2nd Earl of Kimberley (John Wodehouse - son of a leading statesman in Gladstone's Governments) had entered the House of Lords in 1902, and like his father taken the Liberal Whip. In 1918 and 1920 he sent telegrams of support to the Labour parliamentary candidate in South Norfolk, and in 1922 was re-elected to Norfolk County Council, but this time after describing himself as the "Labour" candidate. For these activities he was nicknamed by the press as "the Labour Earl"
In February 1920 the Constitutional Year Book (cited in Twentieth Century British Political Facts 1900-2000 by David and Gareth Butler) identifies the strength of the Labour Party in the House of Lords as One. But the Earl of Kimberley retained the Liberal Whip (despite his support for an opposing candidate in 1920). A seperate Labour Group only fomally existed after January 1924.
Other early members supporting Labour included the 2nd Earl Russell (elder brother of Bertrand Russell, who succeeded him as 3rd Earl) and Earl De La Warr - who was to become Labour Chief Whip (before joined the National Government, and subsequently the conservative Government of Winston Churchill).
It was the advent of the first Labour Government which caused the first formation of a proper Labour Group. Former Liberals such as Viscount Haldane; Lord Gorell; the 2nd Lord Acton (the first death in the group - June 1924); Lord Muir MacKenzie (the first Labour Chief Whip) joined the group and new Peers were created (Lord Olivier - uncle of the actor Laurence Olivier; Lord Thomson and Lord Arnold). Lord Parmoor - a former Tory MP who received a peerage in 1914 from the Liberals, and father of Stafford Cripps, also joined the group.