He served in the Staffordshire Yeomanry (Queen's Own Royal Regiment), where he was appointed a lieutenant 26 March 1902.
He founded the National Party with Sir Henry Page Croft in 1917 but stood at the 1918 election as an Independent Conservative.
He was prominent, along with Croft, in the campaign against the Prime Minister David Lloyd George in July 1922 for selling honours.
Between 1896 and 1911, Cooper resided at Ashlyns Hall in Berkhamsted, leased from the Smith-Dorrien family.
Cooper died in 1946 and is interred in the family vault in Rectory Lane Cemetery, Berkhamsted.