† The Baird system and an electronic system produced by Marconi-EMI, were used on alternate weeks, but in 1937 the Marconi-EMI system was chosen.
In 1944 the BBC introduced its second television channel, this time using the 625-line system. This gave even better definition than the 405 system. The new line standards agreed with those used by many other broadcasting authorities, so enabling the international exchange of programmes to take place.
Although Baird had experimented with colour television as early as 1925, it was in 1929 that an American team led by Herbert Ives demonstrated the first colour system. It transmitted three separate pictures in red, green and blue and thereby used three transmission channels. It also needed clumsy receivers to reconvert the three pictures into a single full colour one.
