How RADAR was born

The plaque reads >

1, Background – In 1931 the Prime Minister, Stanley Baldwin, told the House of Commons that spending on defence against attacking aircraft was a waste of time, as “the bomber will always get through”. Three years later, when it was clear that Hitler was building up Germany’s military strength, a commitiee chaired by Sir Henry Tizard was set up to seek a defence against the threat. The possibility of a “Death Ray” being developed to combat enemy aircraft was actively examined; as an incentive the committee offered £1000 to the first person to kill a sheep with a death ray operating at a distance of 100 yards. The prize was never claimed.

2. Prologue – in February 1935, following an approach from H.E. Wimperis of the Air Ministry, Robert Watson Watt enlisted the help of his senior assistant Arnold Wilkins who calculated that, although a death ray would not be possible, there was a chance of using radio waves to detect distant aircraft. Some four years previously, British Post Office engineers had noticed that aircraft flying through a high frequency beam caused the signal to ‘flutter’. They mentioned it to Arnold Wilkins who was already using reflected waves to measure the height of the ionosphere.

A report entitled “The Detection of Aircraft by Radio Methods” was drafted in which Watson Watt wrote his famous line.  Although it was impossible to destroy aircraft by means of radio waves, it should be possible to detect them by radio energy bouncing back from the aircraft’s body.

At a meeting on 13th February 1935, Air Vice Marshall Dowding was initially unimpressed with the calculations showing only the vague possibility of such a deflection system working. To validate Wilkins’ mathematics, he asked for a practical demonstration to be arranged so Arnold set up what came to be known as “The Daventry Experiment.”

3. Why Here? – This field was chosen because of the available signal from Daventry short-wave radio transmitting station. Although the direct signal was needed for the experiment, it was important that the spot chosen was shielded by hills; otherwise the signal would have been too strong.

4. Setting up – On 25th February 1935 Amold Wilkins and the driver of the Morris commercial van housing the equipment arrived at the site.

They set up two dipole aerials that would pick up any echoes received from the aircraft but were arranged to reduce still further the direct signal from Daventry. These fed into a sensitive receiver housed in the back of the van and the output was connected to a cathode ray oscilloscope mounted nearby. Alignment took longer than expected, it was dark and the lights in the van did not work. The final adjustments were carried out by match light and were only just completed when the BSC station finished transmitting at midnight.

5. The experiment – Five people arrived at the site on the morning of 26th February. Amold Wilkins and Dyer, the driver, came from their hotel at Weedon. A.P. Rowe, the secretary to the Tizard committee, accompanied Robert Watson Watt from London, together with Watt’s nephew Pat, who was left sitting at  the roadside outside the gate. Because Dyer did not have security clearance either, he was sent to a distant corner of the field.

The RAF provided a Handley Page Heyford bomber, K6902, piloted by Flt. Lt. R. S Blucke, to act as the ‘target’ they were hoping to track. It flew over the site and along the direction of the strongest signals from Daventry. On the first run the aircraft was slightly off course and no variation in the signal was seen on the cathode ray screen. It was on the second run that success was achieved. As the Heyford flew over, the line on the screen fluctuated longer and shorter, indicating that radio energy was being reflected from the aircraft above. The variation continued while the aircraft travelled for about eight miles.

6. Success – Watson Watt and Rowe were so pleased with the result that they rushed off towards London leaving Pat behind, returning for him later. The phlegmatic Wilkins and Dyer packed up the equipment and followed later.

Radio Direction Finding (RDF), as it was then known, had arrived, was classified as ‘Top Secret’ and a series of further experiments carried out at Orford Ness on the East Coast.

7. Epilogue – On 1st September 1936 Watson Watt became Superintendent of a new Air Ministry research establishment at Bawdsey Manor near Felixstowe. In 1942 he was knighted for his efforts and added the hyphen to his name. At the same time Arnold Wilkins was awarded an OBE.

Al Bawdsey, Wilkins skippered a team of physicists and engineers who developed the system and installed a chain of 20 stations along the East and South coast of England in time for the outbreak of war in 1939.

Known from 1943 as ‘Radar’, it has gone on to become a vital part of air and sea transport. Without the success first gained at this site the outcome of the Battle of Britain could have been very different and many more lives would have been lost due to bombing