Fighter Control & raid plotting...
What's often overlooked and taken for granted is the established air raid plotting with the sector/central fighter control systems (and the requiired dedicated telephonic commos) were put in place well before the Chain home radar was stood up which increased the 'seeing' distance of incoming raids, the radar could watch raids being assembled over France giving more reaction time to get squadrons into position to intercept etc. Before Chain home the system was entirely human sensed by volunteer sky watchers at many points alond the south coast and inland to track raiders across inland areas.
The planning and established raid precautions were put in place well before radar was a going proposition (work was begun right at the end of WW1 to track Gotha bombing raids but the end of the first war took the build out of the system away as a priority), previously sound location was attempted for dectection of incoming raids but even at the time the limitations of sound location were well known and recognised as being obsolecent at best due to the increased speeds of aircraft rendering plotting innacurate and untimely leading to more confusion.
Interestingly the contrast with continental work on this problem is revealing where French/German/Belgian arrangements were much more piecemeal, mostly consisting of local contacts to airforce officers attached to ground forces HQ's passing on to higher airforce for direction and orders to put aircraft aloft to try to intercept often on a 'enemy aircraft seen over Ostend heading north/south/east/west, no infomation as to numbers, types, or age of infomation etc' which gives the advantage to the attacking raiders. The raid plotting and control allowed by sector/central control backed up by Observer corps & volunteers skywatchers and the increasingly effective Chain Home Radar rebalanced to a certain extent the tactical advantage of the attacking force.