The 3rd London Trophy was a motor race, run to Formula One rules, held on 30 July 1955 at Crystal Palace Circuit, London. The race was run over two heats of 10 laps and a final of 15 laps, and was won by British driver Mike Hawthorn in a Maserati 250F. Hawthorn started from pole position in Heat 1 and set fastest lap in the heat, and also in the final. Vanwall driver Harry Schell started from pole position in Heat 2 and set fastest lap in that heat. Schell was second in the final and Roy Salvadori in a Maserati 250F was third.