A friend of mine still has a broadly 1970s diet, and has packets of Butterscotch Angel Delight at home, Gwylan, so you'll be pleased to learn that it's still about.
For me, it's Truffle, a tiny sweet the size of a single half of a bounty bar, pronounced 'troeffle'. They were advertised with singing Vikings;
"Life would be oewful if we had no Troeffle, our days would be gloomy, our nights would be glum...."
They were only about 10p (the Truffle, not the Vikings) and they were superb. Disappeared years ago.
There used to be this real old fashioned sweet shop here, Willy Wonka chocolate shop style and I remember buying those Truffle things there. That sweet shop had every old/retro sweet going.