We got a second channel from the BBC on 20 April 1964, (the first began broadcasting officially on 2 November 1936 as the BBC Television Service, although television programming from the basement of Broadcasting House began on 22 August 1932, took a short break for the war from 1 September 1939 and resumed on 7 June 1946). TV's weren't commonplace and most people will tell you it was the present Queen's coronation which changed that.
We got a fourth channel, which we imaginatively entitled Channel 4, on 2 November 1982. This gave us our second advertising carrier. Of course things are much altered now, but back to the dawn of British TV advertising...
...this is how it all began: https://www.youtube.com/watch?v=4SmvJmLrvrc
And half a century later, the gorilla we all deserved: https://www.youtube.com/watch?v=SP8E6ouSiC0
(The 'glass and a half' refers to how much milk Cadbury claim is in their product - it really is the world's best milk chocolate :0))