His uncle, the ninth Duke of Argyll, was married to Princess Louise, daughter of Queen Victoria.

From 1919–22, he represented Holborn on the London County Council as a Municipal Reform Party councillor.

When Stanley Baldwin became Prime Minister in May of the same year, Percy was moved to the post of Parliamentary Secretary to the Ministry of Health, which he remained until the fall of the government in January 1924.

When the Conservatives returned to power in November 1924, he was appointed President of the Board of Education by Baldwin, with a seat in the cabinet,[6] and sworn of the Privy Council.

Given charge of policy direction for the government in the latter role, he was often dubbed the "Minister for Thought" by the Press.

[11] Percy married Stella Katherine, daughter of Major-General Laurence George Drummond, in 1918.