Prime Minister Stanley Baldwin, in a prophetic speech to the House of Commons in 1932, declared: “it is well for the man in the street to realise that there is no power on earth that can protect him from being bombed... the bomber will always get through.”

Throughout that decade the dreaded German Luftwaffe threatened to bring devastation to cities across Europe, including the British Isles. Consequently, the British Government was desperate to find an effective method of detection or defence and once again turned to a ‘death ray.’

In 1934 the Air Ministry set up the Committee for the Scientific Survey of Air Defence. CSSAD contained some of the brightest minds of the day, and was chaired by the distinguished Oxford-trained chemist, Sir Henry Tizard, who two decades later would create the MoD’s Flying Saucer Working Party. Tizard’s group scrutinised a number of inventions and ideas, from acoustic mirrors to barrage balloons and eventually turned to the ‘death ray’ which many feared the Germans were already secretly developing.

Following the Grindell Matthews episode, the Air Ministry offered a standing reward of £1,000 to anyone who could build a death ray that could kill a sheep at 100 yards, but no one claimed the prize. On 18 January 1935 H E Wimperis, the director of Scientific Research at the Air Ministry, approached scientist Robert Watson-Watt to advise the government “on the practicability of proposals of the type colloquially called ‘death ray.’” The Tizard committee wanted to know if it was possible to create a beam of electromagnetic energy which could fry enemy pilots in the cockpit, and detonate bombs before aircraft could cause damage, just as Grindell Matthews had proposed a decade earlier.

As Professor R V Jones describes in his Most Secret War, Watson-Watt gave the problem of calculating the amount of power required for a death ray to his assistant, Arnold ‘Skip’ Watkins, who quickly concluded the proposed ray was way ahead of what could be achieved using current technology. When he handed his calculations to Watson-Watt he said: “Well then, if the death ray is not possible, how can we help them?”

Wilkins replied that he was aware that Post Office engineers had noticed that whenever aircraft flew in the vicinity of BBC masts, it caused disturbances to the radio signal. Maybe this phenomenon could be utilised for the detecting enemy aircraft before they reached the British Isles? On 26 February 1935, the day Hitler created the Luftwaffe, Watson-Watt and his assistant set up an experiment at Daventry in Northamptonshire which proved it was possible to detect aircraft by the use of radio waves. As an RAF bomber flew backwards and forwards between two BBC radio masts, the two men sat inside a van watching as a tiny glowing green line flared and swelled on a crude cathode-ray tube display. RDF, or ‘Radar’ (RAdio Detection And Ranging) – the greatest secret weapon in the Allied arsenal - was born. After the demonstration, Watson-Watt declared that Britain “has become an island once more.”

The death ray may never have been a practical weapon, but those who had taken Grindell Matthews’ advice to “think outside the box” and employ their imaginations had stumbled upon a weapon with far greater possibilities that would literally change the world.