There may only have been 3 channels (two BBC and ITV the commercial channel with advertising breaks) but what they showed was watched - and most people then were still watching in black and white. Colour had come in but I did not change over to it until later in 1972. Here again is that first colour television (below): those ugly brown boxes, rented from Radio Rentals (who were on every High Street) - people didn't buy televisions then. Our current large, flat, black, widescreen, HD televisions would have looked like something from science fiction then ...
They are all there, those programmes we remember: DIXON OF DOCK GREEN, the early DR WHO, documentaries like that MAN ALIVE series, LATE NIGHT LINE UP on BBC2 (topical intelligent comment by the likes of Joan Bakewell, Tony Bilbow and oldmovies expert Philip Jenkinson) as well as the "Play of the Month" and "Play for Today" slots. Big series like I CLAUDIUS got everybody talking and garnered huge audiences. Here in the UK, the fourth channel - yes, Channel4 - did not start until 1980 and cable tv much later, Sky began in 1990 and after a shaky start is now very much established.
Of course there was rubbish on then too: THE BLACK AND WHITE MINSTREL SHOW was still running, and comedians like Morecambe and Wise though hugely popular were not to everybody's taste, ditto Dick Emery, Stanley Baxter, DAD'S ARMY. ARE YOU BEING SERVED ... young people didn't depend on tv too much then, in that pre-internet, pre-computer games world, we were too busy being out, at movies, making music etc.
Paul Scofield and Lee Remick in THE AMBASSADORS, 1977.