From 1974, the unique animation style of "Roobarb" a kids cartoon show that was shown just before the early evening news (and thus became popular with adults too).
The marker-style animation with it's constant juddering (apparently called "boiling" by animators) added extra energy.
Richard Briers voiced all the characters, including the endlessly eager and well meaning (if sometimes a bit smug) Roobarb and his rival, the sarcastic pink cat next door named Custard.
It says it ran from the early 70s until 77. What really freaks me out is that everything is somewhat modern except for the ambulances. Those are all just old station wagons with lights on them.
When did ambulances as we know them start being used?