Oddly, I never really got into this one, but I do remember the family being driven absolutely bonkers for a year by 1983's Conundrum – The Cadbury Creme Egg Mystery. We had to eat heaps of the sickly sweets and send off the wrappers in order to receive a book which contained a dozen word and illustration puzzles – each one leading to its own £10,000 golden egg buried somewhere in the UK.
Metro commuter newspaper ran a half-page feature on the new book and published the first puzzle from the book's collection of 14 brain teasers. Mine is in the mail.
(click for clearer view)