 J3902 was launched as "St Brides Bay" on 16 January 1945, and completed on 15 June 1945.After sea trials "St Brides Bay" was commissioned for service in the British Pacific Fleet in June 1945.In July she sailed for Malta, but the proposed deployment in the Pacific was cancelled in August and she was reallocated to the 5th Escort Flotilla in the Mediterranean Fleet.