He was educated at Shrewsbury School and Pembroke College, Cambridge.
He inherited his baronetcy in 1932, on the death of his grandfather, shipbuilder Sir James Marr, 1st Baronet, though he does not use the title.
He studied engineering at Cambridge University, where he graduated in 1942.
During World War II he served as a technician in the Royal Air Force.
His interest in painting developed during his posting to Palestine.Marr participated in two Formula One World Championship Grands Prix, making his debut on 17 July 1954 at the British Grand Prix.
Racing in his private Connaught, he finished in 13th place, but retired from his last world championship race in 1955, after a damaged brake pipe caused him to spin off.
Marr competed in several non-Championship races, with his best results including winning the 1955 Cornwall MRC Formula 1 Race and finishing fourth in the 1956 New Zealand Grand Prix.