Closure
Upon the outbreak of World War II, the BBC closed the Regional Programme and combined it with the National Programme to form a single channel known as the BBC Home Service. The former transmitters of the Regional Programme continued to be used to broadcast this service, but their frequencies were changed and synchronized in order to allow them all to transmit on just two wavelengths (668 and 767 kHz) which, in the event of air raids, could be turned off in sequence to prevent their signals being used as navigational beacons by enemy aircraft.
On 29 July 1945, within 12 weeks of Victory in Europe Day, the BBC reintroduced a regional service, but kept the name "BBC Home Service". The transmitters and frequencies which had been used prewar by the National Programme (the most powerful of which was 200 kHz longwave) were transferred on the same date to a new BBC Light Programme.
Read more about this topic: BBC Regional Programme