I seem to remember that the advertisement went something like...
"Mint Cracknell takes you somewhere cool and green. Somewhere cool and green."
It was a chocolate bar consisting of two small squares held in a small cardboard tray. A little like the cardboard tray that seems to have vanished from Bounty, these days!
It tasted a little like toothpaste - even though I quite liked it.
The inside of the chocolate bar had a crunchy green centre and was probably too "adult" for my childish taste - I think I must have been about 7 - 10 when I first tried it.
I'm not too sure that it was very popular, though.
It disappeared - just like the Bounty cardboard tray did!