In message , Andy Hall
writes

The 70/71 date is because I changed schools at that time, and I
happen to recall all these strange adapters vanished about the
same time. Maybe it was in anticipation of the legal changes?


There was a much more serious problem. Mars bars went up from 4d to
4p in about three months......

Then they announced (with a fanfare) their new size.

It was smaller.

I can't remember, did they turn them upside down like they did with
Wagon Wheels to make them look bigger?

--
geoff