He was called to the bar by the Inner Temple in 1922, joined the Foreign Office as assistant legal adviser in 1925, and was promoted second legal adviser in 1929. He played a key role in the 1930 League of Nations Codification Conference and in relation to the abolition of the capitulatory regime in Egypt in 1934. He advised the British government during the Bretton Woods Conference in 1944, and played an important part in the first three assemblies of the United Nations.