The " English history of electricity".maybe the Chinese don't understand the full potential of Australian red wine.
They then sent RAF people out to buy up all the Hallicrafters S-27 receivers from the Amateur Shops.Efforts in Britain to block the Knickebein system took some time to get started. British intelligence at the Air Ministry, led by R. V. Jones, became aware of the system when the Royal Aircraft Establishment analysed a downed German bomber's Lorenz system and observed it was far more sensitive than required for a mere landing aid. Secretly recorded transcripts from German prisoner of war pilots indicated this may have been a bomb aiming aid. Winston Churchill had also been given Ultra intelligence from decrypted Enigma messages that mentioned 'bombing beams'.
When Jones mentioned the possibility of bombing beams to Churchill, he ordered further investigation. The British codenamed the system Headache. Many in the Air Ministry did not believe that the system was in use. Frederick Lindemann, leading scientific adviser to the government, argued that any such system would not be able to follow the curvature of the Earth, although T. S. Eckersley of the Marconi company had said it could.
Eckersley's assertion was eventually demonstrated after Churchill ordered a flight to try to detect the beams. The RAF lacked equipment capable of detecting 30–33 MHz Lorenz signals, so they purchased an American Hallicrafters S-27 amateur radio receiver from a shop in Lisle Street, London. The receiver was fitted into an Avro Anson and operated by a member of the Y Service. The flight was nearly cancelled when Eckersley withdrew his assertion that the beams would bend round the earth. Jones saved the flight by pointing out that Churchill himself had ordered it, and he would make sure that the Prime Minister would get to know who cancelled it.
The crew were not told any specifics, and were simply ordered to search for radio signals around 30 MHz having Lorenz characteristics and, if they found any, to determine their bearing. The flight took off and eventually flew into the beam from Kleve, on 31.5 MHz. It subsequently located the cross beam from Stollberg (its origin was unknown prior to this flight). The radio operator and navigator were able to plot the path of the beams and discovered that they intersected above the Rolls-Royce engine factory at Derby, at that time the only factory producing the Merlin engine. It was subsequently realised that the argument over whether the beams would bend round the earth was entirely academic, as the transmitters were more or less in line-of-sight to high altitude bombers.
British sceptics started regarding the system as proof that the German pilots were not as good as their own, who they believed could do without such systems. The Butt Report proved this to be wrong; aerial reconnaissance returned photographs of the RAF bombing raids, showing that they were rarely, if ever, anywhere near their targets.