First detection was done in an Avro Anson near Spalding. There had been much arguement between R V Jones and others whether the radio beam could be transmitted over such a distance from the transmitter at Kleve. R V Jones eventually won out because Churchill backed him and demand that flights continued.
The receiver was a highly sensitive Lorenz beam receiver used for blind landings. This was discovered in the wreckage of a Heinkel which was shot down.
The Germans tried ot find out about British radar using a Zeppelin before the war authorised by Luftwaffe signal command under General Wolfgang Martini.
Try the Instruments of Darkness by Alfred Price an ex AEO from V Force.