Lord Denham was the youngest child and second son of George Bowyer, 1st Baron Denham and succeeded to become 2nd Baron Denham upon the death of his father in 1948, his elder brother having died in World War II. He served as a House of Lords whip from 1961 until 1964 under both Harold Macmillan and Alec Douglas-Home. Upon the Conservatives return to power at the 1970 general election, he was once again made a whip under Edward Heath. In 1972, he was promoted to become Captain of the Yeomen of the Guard, the post associated with being the Government Deputy Chief Whip in the House of Lords. He served in this post until the Conservatives left power in 1974. Upon the victory of Margaret Thatcher in the 1979 general election, Lord Denham was made Captain of the Gentlemen-at-Arms, the post associated with being Government Chief Whip in the House of Lords. He held the post for the entirety of the Thatcher years, leaving office six months into the John Major government in 1991.
With the passage of the House of Lords Act 1999, Lord Denham along with almost all other hereditary peers lost his automatic right to sit in the House of Lords. He was however elected as one of the 92 elected hereditary peers to remain in the House of Lords pending completion of House of Lords reform.He was made a Privy Counsellor in 1981.