Some more to ponder:
Dunno if they have been mentioned, but whatever happened to Martin's the newsagents (think they were also known as RS MCColl in some parts of the country.) Shame as they were rather good. I recall two very huge branches, one in Eastbourne, and one in Weymouth. A smaller branch in Lewes became WHSmiths, so maybe they took them over, but the Eastbourne branch became something totally unrelated, can't remember what. And no, not a zimmer frame shop.

Eastbourne is a hip and happening place, actually.
Timothy Whites: Going back a bit here but I remember visiting this place as a kid. The Haywards Heath branch became Dixons. They used to sell cookery stuff if I recalll.
Peter Dominic: Off licence.
Laskeys: Hi fi specialist.
Bit of a tangent but I was amazed when I asked a friend here in York where the nearest Robert Dyas store was and they said "Robert who?" I thought they were a national chain. D.I.Y. store, clearly Southern based only! Weird, it's been a household name in our family since I was a kid. Likewise, I have yet to see a branch of Unwins here in the north.