Postwar broadcast coverage was extended to Birmingham in 1949 with the opening of the Sutton Coldfield transmitting station, and by the mid-1950s most of the country was covered, transmitting a 405-line interlaced image on VHF.[original research?]
On what frequency band was the BBC broadcasting in thie 1950s?
{'text': 'VHF', 'answer_start': 223}