HMS Pretoria Castle (F61): The Liner That Became a Carrier, Then Became a Liner Again

A Passenger Ship Called Up for War

HMS Pretoria Castle began her life with nothing military about her at all. Built by Harland and Wolff in Belfast for the Union-Castle Line, she was launched in 1938 and completed in April 1939 as a passenger liner intended for the England to South Africa run, the kind of comfortable ocean crossing that had very little in common with what awaited her.

The Admiralty requisitioned her that October, within weeks of the outbreak of war, and converted her into an armed merchant cruiser, fitting her out with eight 6-inch guns and two 3-inch guns before sending her into service that November on patrol duties in the South Atlantic, hunting for German raiders and blockade runners in waters her original owners had only ever expected her to cross peacefully.

She sailed from Belfast that December bound for Freetown, and from January 1940 settled into the steady rhythm of convoy defence between there and Liverpool. It was not entirely uneventful work: in 1941 she towed the disabled merchantman Westmoor for three days, intercepted the enemy vessels Monte Gorbea and Desirade the following year, and boarded the Panamanian schooner Reine Marie Stewart after finding her in distress.

In early 1941 she even gained a small air arm of her own, fitted at Southampton with an athwartships catapult and a below-decks hangar for a pair of Fairey Seafox seaplanes, a modest rehearsal, as it turned out, for the far larger aviation role still to come.

From Liner to Aircraft Carrier

As the war progressed, the Royal Navy's appetite for aircraft carriers of every size and type only grew, and in July 1942 the Admiralty purchased Pretoria Castle outright for a far more radical conversion still, sending her to Swan Hunter's yard on the Tyne to be rebuilt as an escort carrier.

She emerged from Swan Hunter's yard with a flight deck, a 354-foot hangar, room for 21 aircraft, eight arrestor wires, two crash barriers and a prototype cordite-fired catapult, defended by two twin 4-inch guns and ten twin 20mm Oerlikon mounts, the third British merchant ship converted into an escort carrier after Audacity and Activity. She commissioned in her new role on 29 July 1943, a truly remarkable transformation for a ship that had begun the war carrying paying passengers to Cape Town.

Both of those have articles of their own here, and they are worth the detour. Audacity was a captured German banana boat, the Navy's first escort carrier and the proof of the whole idea, and she was torpedoed and sunk in December 1941 after less than six months of it. HMS Activity (D94) was a cargo ship taken over on the stocks, and unlike Pretoria Castle she went to sea and killed submarines.

A Carrier That Never Fought, But Changed Naval Aviation

Pretoria Castle fought no naval battles. Instead, she spent almost all her war as a trials and training carrier, a role considerably less dramatic on paper but arguably just as important to the war effort, since every new aircraft type and every new landing technique the Fleet Air Arm wanted to introduce had to be proven safe somewhere before it reached front-line squadrons.

That work was not without real cost. On 26 August 1943, a Fairey Albacore crashed over her side after being waved off; the pilot survived, but two Royal Aircraft Establishment scientists aboard, Dr Townend and Mr Gadd, were killed, a sober reminder that trials flying carried its own genuine dangers even without an enemy in sight.

She did manage one spell of proper wartime escort work, shepherding convoy DS.26 to Iceland and its return convoy SD.46 between late October and early November 1943 with eight Swordfish and six Sea Hurricanes of 825 Squadron embarked, before returning to her trials programme in earnest.

It was aboard Pretoria Castle, on 4 April 1945, that the celebrated test pilot Lieutenant Eric "Winkle" Brown carried out the first ever deck landing by an aircraft with a tricycle undercarriage, a Bell Airacobra, catching a wire, in his own words, "with no trouble at all," though the take-off proved rather more alarming: with the carrier flat out at full speed, he "just managed to stagger off the deck." The day before, Brown had also made the first tail-down catapult launch of a Barracuda using an American-style strop system, a quieter but equally significant first that helped establish a launch technique naval aircraft would use for years afterwards.

The pilot in both of those firsts deserves rather more than a name in passing, and there is a connection worth making. Eric Melrose Brown, universally Winkle on account of being extremely short, which in a cockpit is an advantage, is the most experienced pilot the Royal Navy has ever had or is ever likely to have. He flew 487 different types of aircraft and made 2,407 landings on carrier decks between 1941 and 1953. Both are world records and neither will be beaten, because no air force will ever again build that many types or let one man near all of them.

And he had been aboard Audacity. Brown was flying Martlets from her with 802 Squadron when U-751 torpedoed her on the night of 21 December 1941. Twenty-four men got clear of the ship. Two of them survived the water long enough to be picked up, and he was one. So the man calmly putting a tricycle-undercarriage fighter onto Pretoria Castle's deck in April 1945, and staggering it off again at full speed, had spent a night in the Atlantic three years earlier watching the first ship of this idea go down under him.

On 29 May 1945, pilot John Sproule carried out the first ever landings and take-offs by a glider from a carrier deck, flying a Slingsby T.20 to investigate the turbulent airflow over a flight deck's rounded-down after end. The trial came close to disaster when a wind shift and a stalled winch engine left the glider briefly out of control astern of the ship, saved only when the winch fired back up and hauled the tow line taut again; the turbulence data it gathered proved too poor to use, and the experiment was not repeated.

That August she took the Fleet Air Arm's aviation firsts a step further still, embarking Britain's first jet fighter, the Gloster Meteor prototype DG202, dismantled and brought aboard by road and lighter for a fortnight of engine-running, taxiing and deck-handling trials. No jet actually flew from her deck, but the trial proved a jet aircraft could be safely handled aboard a carrier at all, laying groundwork for the first genuine jet deck landing later that same year.

That landing came on 3 December 1945, and it was Brown again, flying a Sea Vampire onto HMS Ocean (R68) off the Isle of Wight, the first carrier landing by a purely jet-powered aircraft anywhere in the world. Ocean's article tells it properly, including the part where he was ordered to abort and told the captain he had not the fuel to get home, which was not strictly true. Pretoria Castle had done the unglamorous half four months earlier: proving that you could get a jet aboard a carrier, move it about, run it up and not set fire to anything, which is the part nobody makes a newsreel of.

Back to Peacetime, and Back to Being a Liner

Once the war ended, Pretoria Castle's unusual double life came full circle. She was sold back to the Union-Castle Line on 26 January 1946, decommissioned at Belfast that March, and rebuilt once again into a passenger liner, re-entering commercial service as Warwick Castle on 13 March 1947, initially as a mail ship before settling onto the Round Africa route from 1950.

She spent a further fifteen years carrying paying passengers across the same ocean she had once patrolled for enemy raiders and tested prototype aircraft above, before finally being sold for scrap and arriving at Barcelona for breaking on 26 July 1962.

Three Careers in One Hull

Few ships manage even two distinct careers, let alone three, but HMS Pretoria Castle pulled off exactly that: ocean liner, armed patrol cruiser and escort carrier, and then liner again, with a properly significant contribution to the development of naval aviation squeezed in along the way.

It is a career that says a great deal about the sheer adaptability the Second World War demanded of British shipping, civilian and military alike, and about how much could be learned from a carrier that never had to fire a shot at an enemy to make her mark on history.