I worked for Maplin in the Cardiff branch between '98 and 2001 while I was at uni and got to watch the decline from the inside - it all started with an over-eager purchasing manager who got promoted to where he could do some damage. When I first started then the Cardiff branch was one of the "old school" stores with a massive storeroom and a little shop at the front mostly frequented by grubby fingered regulars or people looking for something obscure that they couldn't get elsewhere. We were even allowed to smoke in the storeroom - what luxury!
In '99 the shop was refitted and a large portion of the storeroom was turned into shop space which meant that the building was full of the stupid toys and trinkets that had become the latest rage and all there was no room for the stuff people actually wanted. We lost nearly all the regulars in a matter of weeks when we ended up continually being forced to order in simple parts that always used to be carried in stock. In fairness, the manager normally tried to get requested items carried as stock but there was a limit to the amount of space available - which was reduced from at least 40'x20' to 20'x10' shared with a sales counter.
It is a shame to watch it destroy itself when I used to have such a love for the place. The Chatham branch is still one of the "old school" dingy stores with a big storeroom but it increasingly becoming staffed by muppets and children and they are beginning to discontinue the useful, but obscure, bread and butter lifeblood. I lost count of the times that someone would come in looking for a video drive belt and leave with a bag full of other bits and pieces but, these days, they just leave empty handed.