MV Ancylus was one of nine Anglo Saxon Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier (MAC ship). The group is collectively known as the Rapana class. MV Ancylus was built at Swan Hunter and completed in January, 1935 as an oil tanker for the Anglo Saxon Royal Dutch/Shell line. She was converted to a MAC ship, entering service in October, 1943. As a MAC ship, she had no aircraft hangar, and continued to carry normal cargoes, although operating under Royal Navy control. Only her air crew and the necessary maintenance staff were naval personnel.