Yes, I remember Maplin from the late 1970s when you entered via a tiny security door to the left of the small 'corner shop front window' in Westcliffe on Sea. If my memory serves me right the windows had virtually no display (might even have been whitened out?) and the side door lead upstairs to an Aladin's cave of racking and a few people placing discrete components into envelopes for mailing. They were supremely helpful with finding semiconductor equivalents etc and enabled me to build my first single channel radio control transmitter and receiver.
Later the large glossy stores were more like Tandy, Dixons etc staffed by people who had limited electronics knowledge and were more interested in selling bulk purchase toys than electronics components.
The other shop in Southend at that time was BiPrePak who had some amazing deals on 'service return' equipment which if faulty could often be repaired easily – things like cordless phones, walkman (WHSmiths!), fax machines. My favourite line was their 'failed test' but brand new ex WD (Clansman?) radio battery packs stuffed with excellent D size NiCads with 3.3 AH capacity which worked out at about 1/3 the price of the 1.2AH ones which were all that was available at the time in the High Street (Candice, Uniross etc). Such was the quality of those batteries that I still use one or two of them nearly 40 years later!!
Its good to hear that there remain some specialist suppliers available to serve the hobby trade and where you can go and ferret around for 'goodies'. If anyone knows of such shops in Dorset or Devon do let me know as we are starved down here!