Sir David Arthur Geoffrey Mackworth, 9th Bt. was born on 13 July 1912.1 He was the son of Vice-Admiral Geoffrey Mackworth and Noel Mabel Langford.2 He married, firstly, Mary Alice Robinson-Smith Grylls, daughter of Thomas Henry Grylls, on 20 November 1941. He and Mary Alice Robinson-Smith Grylls were divorced in 1971. He married, secondly, Beryl Joan Cross, daughter of Pembroke Henry Cockayn Cross, on 11 December 1973. He died on 8 February 1998 at age 85.
He was educated at Farnborough School, Nottingham, Nottinghamshire, EnglandG. He was educated at Royal Naval College, Darmouth, Devon, England. He was naval advisor to the Director of Guided Weapon R & D, Ministry of Supply between 1946 and 1949. He was registered as a member of the Royal Institute Navigation. He was managing director of South Coast Rod Rigging Company. He succeeded as the 9th Baronet Mackworth, of the Gnoll, Glamorgan [G.B., 1776] on 18 November 1952. He retired from the military in 1956, with the rank of Commander, late of the Royal Navy.