Sydney Arnold Liberal William Gillis Liberal The 1921 Penistone by-election was a by-election held on 5 March 1921 for the British House of Commons constituency of Penistone in Yorkshire.

The seat had become vacant on the resignation of the Liberal Member of Parliament Sydney Arnold, due to ill-health.

The result at the last General Election in 1918 was; Polling Day was set for 5 March, making it the fourth by-election to be held that week.

Sir James Hinchcliffe received the official endorsement of the Coalition Government.

Pringle reversed the tables on Gillis at the following General Election when the Liberals re-gained the seat from the Labour party;