After his death, his American-born wife Beatrice was elected unopposed to succeed him as Member of Parliament. He served as Parliamentary Secretary to the Ministry of Supply from July to September 1939, when World World War II broke out. A Flight Lieutenant and fighter pilot with the Royal Air Force, he was killed shortly after the Battle of Britain. He was buried at Schoonselhof cemetery, Antwerp, Belgium.
Rathbone was the nephew of Eleanor Rathbone, who had been an independent Member of Parliament for the Combined English Universities between 1929 and 1946, and a staunch women"s rights campaigner.
He was a grandson of William Rathbone, Liberal Member of Parliament for Liverpool and later Carnarvonshire.