His prospects improved when he received endorsement as the official Coalition candidate from Prime Minister David Lloyd George and the Unionist Leader, Bonar Law.
After 1918, the Coalition Government-supporting NDP was wound up and many of its members joined Lloyd George's National Liberal party as did Jarrett.
For the 1922 General Election he switched constituencies, to contest the Labour seat of Dartford, Kent, held by John Edmund Mills.
Jarrett did not join the Liberal party and sought re-election in Dartford as a Constitutionalist.
His next attempt to re-enter parliament came in 1926 when he stood as a Conservative candidate at the East Ham North by-election.
His final attempt to get back into parliament was at the 1929 General election when he contested Edmonton again, this time as a Conservative candidate.