Hardwicke Holderness was born in 1915 in Southern Rhodesia (now Zimbabwe). He studied law at Rhodes University in South Africa and won a Rhodes Scholarship at Magdalen College, University of Oxford, where he spent two years. While at Oxford Holderness joined the University Air Squadron and trained as a pilot. At the outbreak of war he joined the RAF and served with great distinction as a pilot in both training and coastal command, being awarded the DSO, DFC and Airforce Cross, and becoming a wing commander. After the war he joined his father's firm of solicitors in Salisbury, Southern Rhodesia, and remained as senior partner until his retirement in 1975.

In 1954 Holderness was elected as an MP in the Southern Rhodesian parliament under Garfield Todd. Like Todd, Holderness felt strongly that Southern Rhodesia should not follow the South African policy of apartheid. Holderness served as an MP until 1958 when Todd was forced out of government, though Holderness continued to work for constitutional reform during the increasingly turbulent years that followed.

Holderness met his wife Elspeth in Scotland during the war but she was unable to secure a passage to join him in Southern Rhodesia until 1947; soon after her arrival they were married. They had two children and returned to England in 1975.

Holderness died in 2007.