When I was in my teens in 1980s Britain a puzzle was created that came with a prize of 1 million pounds sterling (USD$ 1.6m) for the person who submitted the solution.
It consisted of a pyramid with a triangular base and onto each of the 4 sides it was possible to attach 9 tiles. Each of the 36 tiles contained a red and white pattern and the patterns of adjacent tiles had to match both within a face as well as wrapping around across edges of the pyramid.
I worked for many days to solve the puzzle before giving up and writing a program that ran on a mainframe to generate the solution (I was a computer science undergrad). I posted off my solution only to realise several days later that there was more than one.
What is the name of the puzzle, the name of the company that launched the reward in the UK and the name of the person that won the prize?