Locker-Lampson was elected to the House of Commons at the January 1910 general election as the member for the Ramsey Division in Huntingdonshire, defeating the Liberal incumbent. He stood as a Conservative Unionist on a Tariff Reform ticket. He was re-elected in the December 1910 general election. With the outbreak of the First World War, there were no elections held until 1918, and he continued as an MP throughout this period although absent on active service abroad for much of 1915 to 1918.