Night Raid

by Taylor Downing

  Bawdsey was another ideal site for top secret research – remote and very much at the end of the line, far from the prying eyes of locals or other interested parties. It was on the coast, so radar experiments could be conducted over the sea, and there was a slight hill that helped raise the height of the towers. Furthermore, Bawdsey Manor was a magnificent Victorian mansion built by Sir Cuthbert Quilter, who had made a vast fortune out of the early telephone industry. It had two large wings, parts of the interior were lined with fine wood panelling and there were eight acres of gardens and lawns. Its terrace was bursting with lavender and had terrific sea views. The luxury provided a marked contrast to the bleakness of Orford Ness.

  This time Watson-Watt himself moved to the site, and he and his wife, Margaret, took up residence in a large flat overlooking the sea. Most of the men who were single lived in the Manor. The mansion had two capped towers, one of which, the White Tower, and the stable block became the first laboratories, and 240-foot masts were built on the hills behind the Manor. The site was soon busy with a growing staff and the buzz of ideas and construction. New recruits, often young physicists straight from the universities, joined the team. By the summer of 1936 there were about fifty scientists and engineers working at Bawdsey Manor.

  An air of pioneering optimism pervaded the research station, and although everyone worked immensely hard it was not unusual for the men to break off for a swim in the sea before lunch or a quick game of cricket on the magnificent lawn before dinner. In the eastern wing of the grand house there was a splendid billiard room with a large billiard table that the previous owner offered to sell to the new incumbents. Taffy Bowen bought the table with his own money and donated it to the Bawdsey mess. The atmosphere at Bawdsey Manor was often compared to that of an Oxbridge college where a small community of men (there were no female scientists at Bawdsey at this time) living and working apart, and dining together, dedicated themselves to research and development. Discussions about new ideas often went on late into the night in the grand timbered hall, sitting around a table in front of a roaring fire, just like in a college common room of the day. It was a heady atmosphere, and life at the new research laboratory was good.

  However, progress was not continuous or smooth. In September 1936 a set of trials held at Bawdsey nearly put a stop to the whole development programme. The RAF ordered a fleet of its aircraft to fly out to sea and then approach Bawdsey. The radar operators were not told when to expect them or from what direction they would arrive. For the first couple of days, the trials proved to be a disaster. In front of a host of dignitaries, including Tizard and several RAF chiefs, who had been invited to view progress, the planes came so close that they could be heard overhead before the scientists saw any sign of them on their screens. Dowding himself was present at the fiasco. He was not impressed. Tizard wrote to Watson-Watt with the rebuke that ‘unless very different results are obtained soon, I shall have to dissuade the Air Ministry from putting up other [radar] stations.’1

  Watson-Watt was furious. So many changes and developments were being carried out at the same time in the rush for progress that the equipment was just not ready. However, with a bit of improvisation and the recalibration of some of the transmitters, the trials continued after a four-day delay. This time everything worked perfectly and Bawdsey reported sighting the RAF aircraft with great accuracy.

  It was not clear to Tizard, Watson-Watt and the others what conclusions to draw from these trials. In practical terms the results had varied from dismal failures to great successes. But the Chief of the Air Staff, Sir Edward Ellington, who was desperately keen to get a radar network up and running, having heard the arguments for and against pronounced himself satisfied that the radar system was ‘already proved’.2

  In fact, it was not until further totally successful trials had taken place in April of the following year that the government took the momentous decision to build a chain of radar stations along the east and south coasts of Britain, as a shield facing towards Germany. In the summer of 1938 the full go-ahead was given for the first ever national radar system, known as the Chain Home system.3 The Treasury allocated the vast sum of £1 million to the project. In times of limited government spending this was another sign of the enormous importance that was attached to radar defence. The cost would increase regularly over the next few years, but there now began a race to get a system in place before war came.

  Despite the immense difficulties, the technology was advancing all the time. The team at Bawdsey developed a new type of receiver using a goniometer, a control knob which allowed the operator to determine the direction of the returning radio echoes and the height of objects. With this came a dramatic improvement in measuring height, range and bearing. But it called for a redesign of the layout of the Chain Home stations. Some scientists were worried that the whole system could be jammed, and so it was decided to build four transmitter towers each capable of operating on different frequencies to avoid the problems of one or even two frequencies being jammed. The Air Ministry predicted that the Chain Home system would not be ready until spring 1940. But would that be soon enough?

  The task of finding twenty locations for a radar station, each about forty miles from the next, taxed the minds of many in the Air Ministry in the summer and autumn of 1938. Each site had to be high, near the coast, large and flat. Watson-Watt and his team had final informal approval over each one. When a site was finally selected, power supplies had to be laid on, supply roads built and the station itself, consisting of four 350-foot steel towers and four 240-foot wooden towers, constructed. At the same time, the transmitting and receiving houses had to be built, along with an emergency back-up generator supply house and a home for a full-time warden. Arguments about the design of the wardens’ houses with the Treasury, who wanted to keep costs down, went on for nearly a year. Finally, telephone cables had to be laid by the General Post Office, air raid shelters built, earth revetments constructed to absorb blast, and anti-aircraft defences installed. Meanwhile the clock was ticking and although of course no one knew it at the time, the moment when Britain would be at war again was approaching fast.

  When all of these issues were resolved, opposition to the RAF’s plans came from an unexpected source. The Council for the Protection of Rural England was a powerful body in 1930s Britain and had led the fight against the siting of many of the giant pylons that were planned to carry electricity for the new National Grid, arguing that such constructions were a scar on the face of the countryside. Now they objected to some of the new RAF sites with their huge towers. What was more, several landowners proved unwilling to sell, including local councils who had set the coastal land aside for leisure use. No one was told exactly what the towers were for, although the Air Ministry put out the line that they were radio stations vital for the nation’s defence.

  The Ministry wanted to keep their construction as low key as possible, avoiding publicity. So they were willing to give in to local objections in order to avoid a public row. One planned site was never built and a couple of others were relocated following local objections. The Ministry even wrote into the specifications that the choice of a site ‘should not gravely interfere with the grouse shooting’.4 This phrase is often quoted to illustrate how fuddy-duddy the men from the Ministry were at the time. In fact, it was put in so as not to alienate the powerful landowning classes and to avoid creating a public row.

  Constant changes to specifications, redesigns and reactions to local objections slowed the construction of the Chain Home sites to a snail’s pace. And then, in December 1938, the weather struck. An icy spell with heavy snow and bitterly cold winds closed down many of the high, exposed construction sites. It was a near miracle that by April 1939, seventeen Chain Home stations had been built, their equipment installed and calibrated, and were ready to go into operation. The next few stations to complete the link were constructed through that summer. Although ready, the system was never complete, as the Ministry constantly called for ne
w stations and upgrades were repeatedly made to existing stations. But at least the basic Chain Home network was up and running, with a series of radar stations from northern Scotland to the Isle of Wight, in the nick of time when war came in September 1939.

  The development of the science behind radar and of the technology to use it was, however, only one half of the problem of defending the skies above Britain. Unless effective intelligence could be drawn from the information provided, the Chain Home system would remain a scientific wonder but a practical irrelevance. Watson-Watt realised the need to assess and assimilate the mass of information coming in so as to iron out the slightly different interpretations of height, bearing and distance of enemy raiders produced by the various stations. He proposed the use of filter rooms to turn the radar sightings into usable intelligence.

  For this next stage, Sir Henry Tizard once again came to the fore. He oversaw a series of experiments at Biggin Hill airfield in 1936 and 1937 to introduce a largely sceptical group of senior RAF officers to the new technology. Tizard realised that the detailed intelligence gained from radar could provide officers on the ground with a continuous visual display to reveal the distance, height and bearing of aircraft approaching the coast of Britain. This would give them the vital minutes needed to get their fighters in the air and directed towards the approaching bombers. In the Biggin Hill exercises a squadron of RAF Hawker Hind bombers were instructed to approach Britain on various routes at different times and a squadron of Gloster Gauntlet biplane fighters were ordered to try to intercept them. Before long the fighters were achieving an almost 100 per cent success rate in locating the bombers. So far, so good.

  The first set of exercises were, however, somewhat artificial as the bombers flew on a straight course as they approached Britain. It was highly unlikely that enemy bombers would be so obliging. Therefore, the bombers were told to change course at repeated intervals. This made it much more difficult for the ground controllers to direct the fighters into their path. Again, Tizard’s fertile brain came up with the solution. Knowing that fighters always fly faster than bombers, and using simple geometry, he realised that all the ground controllers had to do was to draw a line between the fighters’ position and that of the bombers and to use this as the base line of an isosceles triangle. The bombers’ new flight path formed the second side of the triangle, and the best interception route for the fighters to take formed the third. The angle at which to direct the fighters was frequently referred to as the ‘Tizzy Angle’ for some years to come.5

  During the course of these experimental exercises the basic working pattern emerged for RAF Fighter Command that was to become familiar during the Battle of Britain. Ground controllers employed large maps laid out on tables and plotters marked the position of approaching aircraft, while fighter aircraft were sent up to intercept them. These too were represented by discs on the map. Officers in a ground control room could as a consequence control an entire aerial battle.

  Although this system of command and control might seem obvious today, it was revolutionary at the time. Pilots were used to flying under their own initiative, and where and how they thought best. They had now to surrender this privilege to ground controllers who would, in RAF parlance, ‘scramble’ them and ‘vector’ them straight to the ‘bandits’ – that is, order them to take off and provide the course for them to steer to the enemy aircraft. This transition did not happen easily or without objection from the pilots. It was fortunate that in Tizard, the RAF had found an exponent of this new form of aerial warfare who had been a flying officer in the First World War. He was able to talk to the crews in their own language. They accepted him not as an outsider but as one of their own. And it was Tizard’s way always to collaborate closely with those he was working with, to understand their perspective and to persuade rather than instruct.

  Gradually the new ideas took hold. During 1936 and 1937, the RAF developed a completely new command and control system for the fighter defence of Britain. The science and technology of radar was married to the requirements of an operational programme and the wizardry of radar was turned into a fighting tool to defend the country.

  But there was still one major problem. While the Chain Home system would provide early warning of the approach of enemy bombers in daytime and could guide fighters to the point at which they could visually identify the enemy bombers, the RAF recognised that it did not have the accuracy to guide fighters close to enemy aircraft if they chose to attack at night. Even with his eyes attuned to the dark, a pilot would never be able to see an enemy aircraft at night even if he flew within a thousand feet of him. Poor weather would reduce night visibility still further. Some sort of airborne radar would be essential to guide the night fighters accurately to their enemy.

  But this posed awesome challenges. The transmitting masts for the Chain Home radar were 240 feet in height. The transmitting equipment weighed several tons. The receiving equipment bristled with valves, control knobs and indicators requiring the interpretation of a highly skilled operator. Bringing all this down to a size that could be fitted inside a fighter aircraft’s fuselage and able to run off the plane’s 500 volt electric supply seemed an impossibility. The sort of miniaturisation that we are familiar with today with microchip technology is a far cry from the use of the large and heavy valves of the 1930s. Nevertheless, Taffy Bowen was told to study how airborne radar might be developed. It was a daunting task.

  However, around the world technology was developing fast and Bowen managed to obtain some powerful ‘doorknob’ transmitting valves from Western Electric in the United States. The introduction of television in Britain by the BBC was taking place at the same time as that of radar and this too was based on the cathode ray tube. Companies like Pye were designing tubes that only weighed a few pounds. With these new devices, Bowen came up with a viable system operating on a wavelength of 1.25 m, and in August 1937 the first airborne radar was given its test flight. The RAF provided aircraft for Bowen to experiment with and these flew out of the nearby airfield at Martlesham Heath. Although the early systems were not sensitive enough to identify aircraft, they proved capable of locating large vessels at sea and became known as Air-to-Surface Vessel or ASV radar.

  Bawdsey expanded rapidly during 1937 and 1938. The RAF established a training school there and its graduates became the first operators of the Chain Home system. As the potential military use of radar spread, army officers arrived to study how radar could be used to assist the targeting of anti-aircraft guns, and naval specialists arrived to study the use of radar to identify enemy ships at sea. The historian David Edgerton has estimated that the total investment in research and development of radar before the war amounted to roughly the same as the cost of building of a battleship, a considerable sum.6 When Watson-Watt moved on to work directly for the Air Ministry, A.P. Rowe replaced him. In charge at Bawdsey he issued a spate of instructions to keep the station run on what he saw as neat and orderly lines. Needless to say, his view on what was acceptable behaviour rarely coincided with that of the boffins who were working there. When Rowe upbraided one scientist for shooting a rabbit by telling him that he could not shoot game on RAF property, he was met with the contemptuous rebuff, ‘Rabbits are not game, they are vermin.’7

  In June 1939, Air Marshal Dowding, who was by now commander-in-chief of Fighter Command, visited Bawdsey to inspect the new air-to-air interception radar that Bowen and his small team had finally come up with. In the back of a Fairey Battle aircraft, a plank of wood was placed across the seat behind the pilot where the observer usually sat. Bowen and Dowding squeezed themselves into this tiny space in the cockpit, with no room to be strapped in or to put on parachutes. They covered their heads with a black cloth so they could see the cathode ray tube screen.

  The aircraft flew to 15,000 feet and the demonstration began with Bowen and Dowding’s plane making approaches to another Fairey Battle from various angles. When the last interception had been made, Dowding asked for the black cl
oth to be removed so he could see how near they were to the target aircraft. Bowen pulled off the cloth and Dowding looked around but couldn’t see the other plane. Bowen pointed out that it was only a few feet directly above them. ‘My God,’ exclaimed Dowding, ‘tell him to move away. We are too close!’ The pilot broke away and headed back to Martlesham Heath. The Fighter Command chief announced that he had been greatly impressed by the demonstration.8 An order for thirty airborne radar sets followed – far too big an order for the tiny research establishment to fulfil.

  Work at Bawdsey Manor ended with the declaration of war on 3 September 1939. Rowe believed that the site on the edge of the North Sea, with its tall radar masts and test towers, was too obvious a target for enemy bombers. He sent out a panicky prediction that German bombs would soon flatten all of Bawdsey. The staff, amounting to about 250 people, were evacuated on the day war was declared and the massive amount of equipment they had built was shipped out. Their new location was to be in Dundee and Perth, where Watson-Watt had arranged with the head of his old university to house the research team. It would prove to be a difficult move and a disastrous location. Radar research came almost to a halt just as the war began and demands upon the technology grew exponentially.