THE BLUE BOOK
Wallace Heaton Ltd. was a very up-market photographic retailer, a sort of photographic Harrods, who were Royal Warrant holders and famously tested everything they sold, thereby adding an extra layer of quality control on top of the manufacturers' efforts.
They published The Photographic Blue Book, generally just known as The Blue Book, from 1949 to 1972, the year in which the company was bought out by Dixons, a sort of photographic Tesco.
The end of retail price maintenance in 1964 must have contributed to the reasons for the takeover. After that, instead of competing on service and quality (as companies had to when prices were fixed by law) they began to compete on price alone; and low prices were hardly compatible with the Wallace Heaton testing programme.