My first thought was: are they flavoured like a hedgehog, or did a hedgehog... ”flavour" them?

I don't personally remember them, but in the pub I used to work in, in the late 90s/early 2000s (about 10-15 years ago) one of the locals always used to ask for them as part of his "ordering crisps joke he did every day for years on end".

"Do you have any hedgehog flavour Crisps?"
"Okay, do you have any helicopter flavour crisps?"
"No helicopter? I guess I'll just have plane (plain) then"

In the 80s my uncle ran a shop. When we went to visit him once he produced these. I think that's the only time I saw them.