The cable ship CS Patrick Stewart was built by W. Simons of Renfrew in 1925 for the government-owned Indo-European Telegraph Company to replace an earlier ship of the same name, built in 1879.[2] The cable laying equipment was supplied by Clarke, Chapman and Company. Patrick Stewart continued to serve with the IETC maintaining the Persian Gulf submarine cables until 1930, when the she was sold by the struggling IETC to the Eastern Telegraph Company amid serious financial problems.[3]
After four years' service with the ETC, Patrick Stewart was sold to the Royal Indian Navy, converted to a survey ship, and renamed HMIS Investigator. Investigator served throughout the Second World War, being based at Calcutta in 1940 under the command of Martin Henry St. Leger Nott from 2 February 1940 to April of that year.[4]
From 1941 onwards, she served as an anti-submarine patrol sloop.[5] For this role, armament, including a 4.7 inch gun, was installed.[6]