A Siren Tour was a night-time mission by the RAF Bomber Command, mostly in northern Cambridgeshire, involving three or four two-engined fast bomber aircraft, to set the German air-raid sirens off in the middle of the night, so waking up the whole German town at three o'clock in the morning.
The raids were carried out by RAF bases in Cambridgeshire and Huntingdonshire, from the Light Night Striking Force.
These were small bombing raids, often in the middle of the night, to get the population in the German town out of bed, on the sound of a Fliegeralarm, to intentionally upset the nocturnal rhythm by false alarms of the German factory workers; night shift workers would have to go to the shelters, and day shift workers had their sleep disturbed.
The two-engined bomber aircraft were largely invincible from any attack; for the first six hundred Mosquito missions over Germany, only one was shot down.
Once the bomb was dropped, the twin-engined bomber could return to Cambridgeshire at 400 mph, being invisible to radar.