I remember those! The Radiospares catalogue used to be a thin A4 magazine type thing, before growing into a phone book sized boxed set, after which it was online only. Originally, R/S sold spare parts to the radio & TV repair trade, and were very touchy about who could open an account with them, later on they opened up and now they’re a general full service broadline distributor.
The decade PCBs date to the early stages of the transition. You could make a counter using them, or most people used them to make clocks. The really adventurous could make a DVM, even!