Leslie was born 14 August 1922, at Aykley Heads in Durham City, the son of John Lynn Marr and Amelia Rachel Thompson. Leslie inherited the Baronetcy from his grandfather, Sir James Marr, upon his death on 24 November 1932, but he does not use the title. He was educated at Shrewsbury and Pembroke College, Cambridge. He was a Flight Lieutenant in the Royal Air Force, Technical Branch (Radar).
He started painting in Palestine during WW2. After the war he was taught by David Bomberg at the Borough Polytechnic. In 1948 He became a member and secretary of the Borough Group, under Bomberg's presidency, and took part in many of its exhibitions. He married Bomberg's step-daughter, Dinora Mendelson.
He raced his Connaught in national events during 1952-53, before trying his hand against tougher opposition in 1954, when he gained his greatest success in Libre events, placing third in the Glover Trophy, and third in the F2 class in the Aintree 200 and third in the Oulton Park International 'Gold Cup'. He finished 13th in the 1954 British Grand Prix. It is worth mentioning that he was the third British car across the line, racing an F2 car against the F1 spec cars from France, Germany, Italy
In 1955 Marr took delivery of a B-Type model, the (in)famous streamliner, and won his first outing in the car at Davidstow in Cornwall. Leslie does admit that there was not much opposition, Peter Collins was entered but did not arrive, however he did raise the lap record by nearly 10 seconds! He also took class wins class wins at the Brighton speed trials and Shelsley Walsh.
He failed to finish the British GP that year, and raced little until early 1956, when he drove splendidly to finish fourth in the New Zealand GP, starting from the back of the grid without benefit of practice. He then took third place in the Lady Wigram Trophy at Christchurch.
The last time he drove the B-Type was the final event in N.Z. at Invercargill. He was on pole, but after being hit in the face by a stone during the race, he spun into a ditch and wrecked that amazing, and as Leslie mensions, very expensive body.
He is a professional artist who lived on the Isle of Arran until about 20 years ago when he moved to Norfolk. Married three times, the last time in 2002, to Maureen Monk, he has two daughters by his second marriage to Lynn Moynihan. He also has 3 grandchildren.
He is represented by; Piano Nobile, 129, Portland Rd., London, W11 4LW, Tel. 0207 229 1099