WH Smith have been around a long time, Beatties for a model shop, John Menzies (geographical area dependent). Tesco, Presto for supermarkets. BHS, C&A in larger towns. Local family owned butchers, greengrocers (there was a chain but I can't remember the name). Most banks have been around a long time too.
You can sometimes find pictures of a high street in the area you're modelling on flickr, if you do the advanced search and restrict the dates of the results too.