HMS Pretoria Castle (F61) was an armed merchant cruiser and escort aircraft carrier

Escort aircraft carrier

The escort aircraft carrier or escort carrier, also called a "jeep carrier" or "baby flattop" in the USN or "Woolworth Carrier" by the Royal Navy, was a small and slow type of aircraft carrier used by the British Royal Navy , the Imperial Japanese Navy and Imperial Japanese Army Air Force, and the...

 of the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 that saw service during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. She had previously been the ocean liner

Ocean liner

An ocean liner is a ship designed to transport people from one seaport to another along regular long-distance maritime routes according to a schedule. Liners may also carry cargo or mail, and may sometimes be used for other purposes .Cargo vessels running to a schedule are sometimes referred to as...

 Pretoria Castle of the Union-Castle Line

Union-Castle Line

The Union-Castle Line was a prominent British shipping line that operated a fleet of passenger liners and cargo ships between Europe and Africa from 1900 to 1977. It was formed from the merger of the Union Line and Castle Shipping Line...

; built at Harland & Wolff shipyards in Belfast

Belfast

Belfast is the capital of and largest city in Northern Ireland. By population, it is the 14th biggest city in the United Kingdom and second biggest on the island of Ireland . It is the seat of the devolved government and legislative Northern Ireland Assembly...

, Northern Ireland

Northern Ireland

Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...

 and launched in 1938.

She was requisitioned by the Royal Navy in October 1939, and converted to an armed merchant cruiser with 6 inches (152.4 mm) and 3 inches (76.2 mm) guns, entering service in November 1939.