The service initially used two different, incompatible systems which were alternated weekly. These were the 405-lines interlaced scan from Marconi-EMI, and the 240-lines progressive scan from Baird Television Ltd.
Initially the press favoured the Logie Baird system because there was a delay of 60 seconds before the image would appear on screens. At a press demo of the technology this meant that the journalists could dash around the camera and see themselves still on the screen. However, the Logie Baird system was deemed inferior and was dropped after only three months.