It is rare for an inventor to produce something entirely new and original on his own. It will be inspired by something that everyone earlier has failed to notice, but more usually it results from achieving a successful application of the work of earlier pioneers.
Heinrich Hertz (1857-1894) showed that electromagnetic waves in what we term the "radio frequency" band can be reflected, refracted, and focused just like light.
In 1904 Christian Huelsmeyer successfully set up his anti-collision Telemobilskop on the Hohenzollern Bridge in Cologne to detect ships passing below.
In the 1930's the French liner Normandie was fitted with an iceberg detector in the form of a radio transmitter and receiver.

In 1935 Robert Watson Watt (1892-1973), Superintendent of the Radio Research Station at Slough, was asked by the Air Ministry if it would be possible to use a radio beam as a "death ray" to injure the pilots of enemy bombers. He asked Mr. Arnold Wilkins to calculate the amount of RF power required to raise the temperature of 8 pints of water from 98° to 105° Fahrenheit at a distance of 5 km. The result was too large to be applicable, so Watson Watt asked Wilkins for any other suggestions. Strangely, inspiration didn't come from his work in measuring the height of ionised layers in the upper atmosphere, but from the fact that VHF beams used for Post Office communications suffered fluctuation in strength when aircraft flew through them.

Thus it came about that on the insistence of Air Marshal "Stuffy" Dowding an experiment was conducted to demonstrate that a bomber could be detected by radio reflections. Wilkins fitted a receiver, an oscilloscope, and trace recorder into an old ambulance, which was driven northwards along the A5 road, towards the BBC Daventry empire broadcasting station, which was to provide the transmission source. About 7 miles SE of Daventry, they turned off along the B4525 road towards Litchborough for about a ¼ mile, got permission from a farmer to park and work in his field, and set up their aerials. Unfortunately the light inside the ambulance wasn't working, so they had to work by the light of matches to adjust the equipment, and in the difficult circumstances failed to note that the recorder wasn't operating, so a permanent record of what was to be a historic signal was lost.

The next day, Mr. Dyer the ambulance driver, who wasn't allowed to watch or know what the demonstration was about, had to go for a walk, while Wilkins tuned into the 49 metre transmission to Australasia. With Watson Watt, and AP Rowe (a member of a secret government defence committee) as observers, the three waited for Heyford bomber J9130 to fly through the beam during a broadcasting test period. The received signal displayed on the oscilloscope, satisfactorily fluctuated in amplitude as the plane proceeded. You will probably have seen the same effect if you once had a VHF television.

Now a stone has been positioned on the road nearby to commemorate the event, with a plaque reading:-

The plaque also has a picture of a HP Heyford bomber.

While there is truth in this, another important element was the reporting system set up earlier for sound detection, and visual sightings by the Royal Observer Corps.

During October 2007 I received an E-mail from Brian Leathley-Andrews, otherwise known as G8GMU, who had come across our website and thought we might like to use a photo he had taken of this commemorative plaque which I am pleased to include below.   You can find out a bit more about Brian and his interests by clicking on the following link: http://www.andrewphotographic.co.uk/g8gmu2.htm .

References:
Orfordness — by Gordon Kinsey — Terence Dalton Ltd. Lavenham, Suffolk
SAGA Magazine — December 2001

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