[3] He did not stand in 1885, but having joined the Liberal unionists in 1885 he unsuccessfully contested Berwick-Upon-Tweed in 1886,[4] Sunderland in 1892,[5] and a by-election in South East Durham in February 1898.
[6] He was returned to the House of Commons after a fifteen year absence at the 1900 general election, when he defeated Joseph Richardson, the Liberal winner of the 1898 by-election.
Lambton was re-elected unopposed in 1906, but lost the seat by a wide margin to a Liberal candidate in January 1910.
Lambton married Beatrix Bulteel (1859 – 27 April 1937), his second cousin once removed, on 26 May 1879.
They had six children: Lord Durham died on 31 January 1929 at the age of 73, having held the earldom for only 4 months, and was succeeded in the title by his elder son, John.