He was the elder son of Count John Francis William de Salis (1825–1871), a diplomat and numismatist of Hillingdon, and Amelia Frances Harriet (1837 – 8 January 1885), eldest daughter of Christopher Tower, JP DL MP, (1800–84), of Huntsmoor Park, Iver, Buckinghamshire, and of Weald Hall, Essex.

[1] After being educated at Eton (1877–1882, Edward Compton Austen Leigh's house) he was nominated an attaché in the diplomatic service on 20 November 1886.

From August 1894 he served in Cairo under Lord Cromer in charge of the agency there when the Dervishes were active (he was granted an allowance for knowledge of Arabic on 2 April 1895).

He was employed between 1901 and 1906 at the Foreign Office in London, and appointed a British Delegate for negotiation of a new Commercial Convention with Romania on 7 September 1905.

In the House of Commons, Ronald McNeill repeatedly asked about production of the Report and De Salis's possible arrest.