Downing switched to single seaters in 1952 racing a Connaught A-Type, and won the Madgwick Cup at Goodwood and second place at the Grand Prix des Frontières at Chimay Belgium, where he lost the lead at the end of the race several metres before the finish line. He finished ninth in his first World Championship event at Silverstone, but had run fourth in the race before spinning while avoiding a backmarker. He competed in the later that year, but retired from an oil-pressure problem. He switched to an Aston Martin DB3S for 1953, but decided to retire from racing soon after.