Ewen Edward Samuel Montagu CBE QC DL (29 March 1901 – 19 July 1985) was a British judge, Naval intelligence officer, and author.

[2] He was educated at Westminster School before becoming a machine gun instructor during the First World War at a United States Naval Air Station.

From there he was assigned to the Royal Navy's East Yorkshire headquarters at Hull as an assistant staff officer in intelligence.

[6] Montagu served in the Naval Intelligence Division of the British Admiralty, rising to the rank of Lieutenant Commander RNVR.

[7] Montagu had the idea of having a corpse dressed as a British officer wash ashore in Spain, carrying faked papers revealing plans for invasion of Greece (the real target was Sicily).

Montagu manufactured a false identity, "William Martin", for the body of Glyndwr Michael to have in his pockets: military ID, theatre ticket stubs, love letters and a photo of his fiancée, bills from a tailor and jeweller.

Montagu also wrote Beyond Top Secret Ultra, which focused more on the information technology and espionage tactics used in World War II.

[11] Before the Courts Act 1971 Montagu was Chairman of the Quarter Sessions for the Middlesex area of Greater London[12] and recorder in the County of Hampshire.