[2] Mackworth-Young was the son of Gerard Mackworth Young, a civil servant in British India.
[2] Upon the outbreak of the Second World War, Mackworth-Young joined the Royal Air Force.
[3] He saw active service in the Middle East and in the Normandy Campaign, leaving the RAF as a Squadron Leader in 1948.
In 1955, Mackworth-Young was appointed to be a librarian in the Royal Household at Windsor Castle.
[6] From his retirement in 1985 to his death he was given the honorary title of Emeritus Librarian by Elizabeth II.