Carless was born on 22 April 1925 in Nainital, British India, to Henry Alfred Carless, CIE, who served as a police officer in the Indian Civil Service (Inspector-General of Police, Ajmer-Merwara and advisor to the Resident of Rajputana) and his wife, Gwendolen Pattullo.
[2] Carless was commissioned in January 1944[3] in the Intelligence Corps and posted to Teheran as a staff officer with the 12th Indian Division, but volunteered for active service, first with the 5th Infantry Division, and later, in the last nine months of World War II he served in the 15th Scottish with the 6th Battalion of the Royal Scots Fusiliers.
Between 1958 and 1961 he worked in the Information Research Dept, FO, and as Private Secretary to Lord Dundee, the Minister of State for Foreign Affairs[1] (1961 to 1963).
He headed the Latin America department of the Foreign Office from 1973 to 1977, before his ministerial appointment as chargé d'affaires in Buenos Aires, Argentina, from 1977 until 1980, where he monitored the disputed sovereignty of islands in the Beagle Channel, and the Falklands.
Following his retirement in 1985, Carless served as Vice-Chairman of the South Atlantic Council based in London, and between 1994 and 1996 he chaired the influential series of Argentine-British Conferences which helped to re-instate full diplomatic relations between the two countries after the Falklands war.