While heading the Factory Department at the Home Office, he was one of the principal movers behind the establishment of the International Labour Office and initially served on its Governing body. He was also influential in reorganised the Factory Department and establishing an industrial museum, the Home Office Industrial Museum, to promote worker safety, health and welfare. Delevingne was sent as part of the British delegation to international labour conferences in Bern in 1905, 1906 and 1913, in Washington, D.C. in 1919, and in Geneva in 1923, 1928 and 1929. British delegate to the Labour Commission of the Paris Peace Conference, 1919.