de Havilland Mosquitoes in BOAC Service.

Very few countries around the world managed to avoid the influence of the Second World War as it ravaged and rampaged its way across the globe. One such nation that did manage to keep its borders secure though was Sweden, a place that became known as a safe haven for downed airmen or those trying to escape the clutches of the Nazi tyranny that would engulf vast swathes of the European continent. Surrounded by conflict and declared neutral, Sweden was to all intents and purposes cut off from the rest of the world.

However, Sweden was a country reliant on imports and exports, a reliance that led to extensive negotiations between herself and both the axis and allied powers who effectively blockaded her supply routes. Through these negotiations she achieved an  agreement to the rights of passage for ‘safe-conduct traffic’, an agreement that allowed the passage through hostile waters of shipping, allowing the exports of paper and wood from Sweden, in exchange for imports of food and oil.

Sweden’s role in the Second World war was largely political. If she was to survive she was going to have to forge safe links beyond her closest Scandinavian neighbours. Fearing she would be sucked into war and absorbed into a Europe ruled by Germany, she turned to Britain with a view to forging a safe airway between Stockholm and Scotland.

Discussions around the opening of the Swedish air routes began prior to war breaking out, negotiations between the Chairman of Britain’s Civil Aviation Authority (CAA), Sweden’s airline company AB Aerotransport (ABA) and Germany’s Hermann Goring, eventually led to an agreed flight once per week from Stockholm – Oslo-Stavanger-Perth. However, ongoing Swedish concerns led to long delays in activation of the service, even though a successful test flight involving a Junkers 52 had taking place on November 27th 1939.

The Swedish ABA were to run the operation, initially using three DC-3s (named Gripen ‘Griffin’, Gladen ‘kite’ and Falken ‘falcon’) painted bright orange and clearly marked Sweden/Schweden in large black lettering to prevent attacks from either side on a neutral aircraft. Throughout the war though this link was tenuous at best, heightened German aggression and fearsome weather often being the determining factors for the safe passage of the aircraft between the two countries. German restrictions on both freight and passengers angered the Swedes, who defiantly disobeyed their rulings. This decision led to a number of Swedish operated aircraft being attacked and shot down.

By 1945 the Swedes decided it was now too dangerous to fly, particularly with trigger happy defences and over keen allied pilots. The airspace around Sweden’s near neighbour Norway, had become a cauldron of  fire, and so the service was eventually closed down.

However, this official Swedish run route was not the only airway that operated between the two countries. The Norwegians also ran a service albeit reduced, as did the Americans later on in the war with five stripped out B-24 Liberators. Another service however, a ‘British’ service, also operated, but this was much more of a clandestine role than that of their Swedish counterparts.

At the time Sweden was a producer of iron but more importantly ball-bearings, a  commodity essential for any moving parts in machinery; whether it be a simple tool or a more complex engine, without them machinery simply wouldn’t work.

Ball-bearings in Sweden were all manufactured by one company, Svenska Kullagerfabriken AB (SKF), who before the war, exported around 9% of her total output to Germany with another 9% going to the United Kingdom. During the war however, this balance dramatically fell heavily on the side of Germany with as much as 65% of her total output ending up in German hands by 1943.*¹ This imbalance was primarily due to the exports that were received in the occupied territories, falling into German hands, and being diverted into Germany’s own industrial operations.

Britain however, also needed these ball-bearings, and was perhaps more keen on maintaining this link than many would have initially thought. Having her supply line to Swedish goods cut was going to hit Britain hard. Britain needed all the ball-bearings she could find, and so Sweden was vital to this supply. So desperate were the British  authorities to obtain these components that they mounted two naval operations,  ‘Rubble‘ and ‘Performance‘, both of which turned out to be disastrous in terms of both the loss of life and the loss of shipping.

There were many other reasons why Britain wanted to maintain this link though, one was the expansion of its resistance operations across Scandinavia, Sweden providing a safe passage for agents entering and leaving the region safely, a move that was just as important as it was for returning escaped or interned airmen of the RAF and later USAAF.

Furthermore, Britain needed to ensure that Sweden was receiving as much British propaganda as it was German. If this line were to be severed, there would be a chance that the imbalance in material may have detrimental effects on Sweden’s future as the war developed.

In late 1939 flights began in secrecy, operated by British Airways Ltd, who used three Junkers 52 transport aircraft and one Lockheed Model 14 Super Electra (the forerunner of the Hudson) named ‘Bashful Gertie‘ (G-AGBG). Like the Swedish operation, these flights took place between Perth and Stockholm via Norway and were flown by civilian crews in civilian marked aircraft. However, this route was subsequently closed when one of the aircraft was attacked by a Luftwaffe fighter, and another was captured in Oslo when the Germans invaded Norway.

Then in 1939/40 the two British aviation companies, British Airways Ltd and Imperial Airways, merged to form the British Overseas Airways Corporation (BOAC), a civilian operation that would go on to serve as Britain’s leading national airline for many years after the war’s end. The amalgamation of these companies was an important step forward leading to the reinstatement of the Swedish route, this time using the military base at RAF Leuchars in Fife.

Also piloted by Swedish or Norwegian aircrew, the idea behind the route was to pass POW mail and propaganda (magazines, newspapers etc) into Sweden where it could be forwarded to prison camps in occupied Europe. However, constantly aware of the need for ball-bearings and the fact that Sweden was a major supplier of them, plans were put in place for returning aircraft to be refuelled and filled with ball-bearings before returning to Leuchars. This run hence became known as the ‘ball-bearing run‘.

In these early years of the war, BOAC operated other similar aircraft types, these included C-47 Dakotas, converted Whitley IV bombers and Curtis Wright C46 aircraft, but their lack of speed and manoeuvrability left them vulnerable to Luftwaffe attacks. It soon became clear that a new and much faster type was needed and so BOAC began to put pressure on de Havilland for their new Mosquito.

A Whitley bomber in BOAC markings *⁷

A trial flight was undertaken using an unmarked Mosquito of 105 Sqn (DK292) on August 6th 1942 (there is some confusion over this exact date), flown by  Fl. Lt. Parry and P. Off. Robinson, the results of which showed the aircraft to be highly suitable for the purpose of the flights. The journey from Leuchars to Stockholm covered some 800 miles was, on average, completed in around 3 hours.

On 15th December 1942 the first civilian operated model of the aircraft arrived at Leuchars. A Mosquito PR.IV ‘DZ411’,  it was assigned the civilian registration G-AGFV, and began flights to Stockholm on 4th February 1943. After this, it was joined by six other Mosquito MK.VI aircraft between April and May (all being given the sequential registrations G-AGGC to AGGH) with a further three in April 1944.

The incredible carrying capacity of the Mosquito, which would be proven later in the war, would allow for up to 650Kg (10 -12 crates) of ball-bearings to be carried in the aircraft’s bomb bay.

The opening of such a link was kept very secret, the British not wanting the Germans to know about the new revolutionary Mosquito, nor their important cargo. However, keeping such an operation from German intelligence was difficult, if not impossible, and soon they discovered that the flights were again taking place between the two countries. Now embroiled in a political stand off, the Germans put pressure on neutral Sweden to put a stop to these flights, insisting that they were giving the British an advantage, and that as a neutral country, they should not be allowing British aircraft to land on Swedish soil. The Swedes maintained that the service was purely civilian and controlled solely by the Swedish authorities, to which the Germans threatened to inform Hitler thus rendering the aircraft legitimate military targets. Fearing that the British would in turn close the passage for the safe-conduct traffic, the Swedes ignored the German threats and so the service continued.

However, so as to not infringe or violate Sweden’s wartime neutrality, it was vital that the Mosquitoes remained unarmed for these operations. But that made any aircraft on this run a potential ‘sitting duck’, even though, like their Lockheed predecessors, they carried BOAC insignia and were flown by civilian aircrew.

So all of these aircraft had to be changed from military status to civilian, this required the removal of all traces of armament. Modified at Hatfield – the home of the Mosquito – the resultant weight loss altered the aircraft’s centre of gravity and so additional ballast had to be added to prevent changes in the aircraft’s flying characteristics.

The first example DZ411, was a Mosquito B.IV Series II, powered by two Merlin 21/23 engines built under the contract 555/C.23(a) and converted to a PR.IV at Hatfield prior to its delivery to BOAC at RAF Leuchars. It would go on to serve until early 1945 with BOAC before presumably returning to RAF ownership.

The first of the next batch, all FB.VIs, was ‘HJ680’ another example built at Hatfield under the same contract 555/C.23(a) but with Merlin 23/25 engines. This aircraft was initially passed to BOAC at Bramcote on April 16th 1943, receiving the registration G-AGGC before flying on to Leuchars immediately after. On the 18th, on the return leg of its maiden flight for BOAC, it was chased by enemy fighters, but its speed and agility allowed the Mosquito to escape unharmed. It was eventually removed from service on November 30th 1944, but remained at Leuchars in case a ‘spare’ aircraft was urgently needed. This particular model was the longest serving Mosquito in BOAC’s service, being taken off the civil register on January 4th 1946, whereupon it was passed to 22 Maintenance Unit. On June 15th 1950, the example was eventually sold as scrap to the John Dale Scrap merchants.

The next aircraft ‘HJ681’ arrived at the same time, and remained in service until January 1944, under the civil registration G-AGGD. This particular aircraft crash landed in Sweden and was reduced to spare parts.

‘HJ718’ arrived on April 24th and was given the registration G-AGGE, it served until June 1945, whilst ‘HJ720’ (G-AGGF) crashed into high ground at Invernairk, Glen Esk on 17th August 1943, killing both crewmen Captain L.A. Wilkins and Radio Operator N.H. Beaumont. A further FB.VI, ‘HJ721’ (G-AGGG) also crashed, this time on the return leg only a mile or so from Leuchars on October 25th 1943, when the port engine failed. Both crewmen, Captain Hamre and Radio Operator Haug, lost their lives along with their passenger Mr Carl Rogers.

The last FB.VI ‘HJ723’ also built under the same contract as the other models, arrived on the 2nd May 1943, and would operate until the end of June 1945 as G-AGGH . It was subsequently handed over to the RAF and eventually presumably disposed of.

By the end of May 1943, a total of nine Mosquitoes would have been modified and delivered to BOAC at Leuchars*⁵.

DH98 Mosquito G-AGFV (DZ411) MkIV BOAC on 8th January 1943 (© 2021 BAE Systems)

In June 1943, with the need for ball-bearings increasing, two Mosquitoes departed Leuchars with two very important dignitaries onboard. Firstly the British president of the Swedish SKF airline and secondly a ball-bearings expert from the British authorities, who were going to negotiate the delivery of further supplies to Britain.

In order to accommodate these additional passengers the bomb bay of the aircraft had to be converted, thus allowing them to lay on their backs on padded felt*⁶. An additional reading lamp was fitted, along with an oxygen supply, intercom and even coffee. The passenger would have a piece of string the other end of which was tied to the pilots leg, and should the conditions  in the bomb bay become too uncomfortable, they would pull the string.

These operations were very soon regularly carrying human cargo. On the outward leg mail, newspapers and other written material held within its bomb bay, would be deposited in Sweden, the aircraft would be refuelled and stocked up with either human cargo (allied aircrew, special agents or scientists), ball-bearings or a mix of the two. The faster and far more agile Mosquito would, in most cases, be able to out run any opposing Luftwaffe fighter that should, and indeed did, try to intercept the aircraft whilst on one of these flights.

One such notable passenger who was carried back from Sweden was the nuclear physicist Niels Bohr whose work on atomic structures and quantum theory had won him the Nobel Prize in Physics in 1922.*⁴ His journey almost cost him his life though after he failed to operate his oxygen mask correctly. Only when the failed to respond to the pilot’s attempts to contact him, was action taken and the aircraft reduced altitude allowing Bohr to breathe normally and regain consciousness. Bohr went on to work on the Manhattan project, an American project that led to the development of the atomic bomb that would end the war, and plunge the world into the nuclear age.

A large number of other significant people were also carried by these Mosquitoes, Sgt. Jack Byrne who went on to be a  founder member of the SAS, after being shot in the face, bayoneted in the groin and detained in several prisoner of war camps, was one such person repatriated to Leuchars. Three of those who escaped in the famous ‘Wooden Horse‘ escape were also returned via Mosquitoes from Sweden; as where Norwegians Peter Bergsland and Jens Muller two of the three to escape in ‘The Great Escape’.

In ‘Operation Gunnerside’, the SOE operation to blow up the German heavy Water plant in Norway (featured in the film ‘The Heroes of Telemark‘), six of the team were repatriated using this route. A key player in this operation was Leif Tronstad, a Norwegian Physicist who was also flown to Scotland to provide vital information about the German efforts to produce heavy water at the plant.

A considerable number of British personalities were also flown into Sweden using this method; T.S. Elliot, Sir Kenneth Clarke and even the Bishop of Chichester were flown into Sweden this way.

Sgt. Jack Byrne, was shot, bayoneted and imprisoned. He fought at Dunkirk, on D-Day, in North Africa and at the Battle of the Bulge and then went on to be a founder member of the SAS.*2

By the end of 1943, 157 such flights had been made, 129 of which were by these Mosquitoes. A total of some 110 tonnes of freight (a mix of human and mainly ball bearings) had been carried.

Even though these flights were highly successful, a few aircraft were lost. In Mid August 1944, G-AGKP ‘LR296’ a former 27 MU aircraft was lost when it crashed into the sea nine miles from Leuchars. All three on board, Captain G. Rae, Radio Operator D.T. Roberts and Captain B.W.B. Orton (himself a BOAC Mosquito pilot), were killed as it approached Leuchars on its return flight from Stockholm.  The crash was believed to have been caused by the aircraft’s structural failure, the aircraft having been repaired previously after an accident in January. The total number of aircraft being used by BOAC reached fourteen, with five of these crashing including one G-AGKR ‘HJ792’ being lost at sea in August 1944 with no trace of either the aircraft or crew ever being found.

On 17th May 1945 the service officially ceased. Between 1941 and the war’s end, 1,200 of these trips had been made, many by the Mosquitoes. The service between Sweden and Scotland had been a vital link between the two countries not only for the supply of ball-bearings but a life line for escapees and special agents. For these Mosquitoes it was a remarkable achievement for an aircraft that would prove itself to be one of the war’s most incredible designs.

de Havilland Mosquitoes used by BOAC*³:

DK292 – The first Mosquito to fly the Leuchars – Stockholm route
DZ411 – G-AGFV flew to 1945
HJ667 – G-AGKO flew to 1945
HJ680 – G-AGGC flew to 1946
HJ681 – G-AGGD crash landed Sweden 1941
HJ718 – G-AGGE flew to 1945
HJ720 – G-AGGF crashed Invernairk 1943
HJ721 – G-AGGG crashed near to Leuchars 1943
HJ723 – G-AGGH flew to 1945
LR296 – G-AGKP crashed near Leuchars 1944
HJ792 – G-AGKR lost at sea 1944
HJ898 – Crew trainer retained RAF serial flew to 1945
HJ985 – Crew trainer retained RAF serial returned to RAF 1944
LR524 – Crew trainer retained RAF serial returned to RAF 1944

RAF Leuchars appears in Trail 53.

Sources and further reading.

*¹ Martin Fritz (1975) Swedish ball-bearings and The German war economy,
Scandinavian Economic History Review, 23:1, 15-35, DOI: 10.1080/03585522.1975.10407803

*² Photo from “Think Scotland website”  accessed 12/3/21

*³*⁶ The Mosquito Page Website accessed 12/3/21

*⁴ For additional information and pilot stories about the ‘ball-bearing’ run see the Royal Institute of Navigation Blog.

*⁵ Thirsk, I. “de Havilland Mosquito – An illustrated History Vol.2“, Crecy 2006

*⁷ Photo from Aircraft Enthusiast Group Website.

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