I grew up around this area - it really is a gem of a place. The interior is so cool, with sort of organised clutter everywhere. They have a little garden and they serve food. Its not the best in the world, but the whole experience there is great.
G.F. Smith's permanent showroom, in Central London. Visits are by appointments only — But I would definitely recommend making the visit. All of their stocks are beautifully archived, along with example publications, and a rotating series of paper installations in both the window & basement, courtesy of Made Thought.
This is one of the only buildings in London that can lift depression. Each concrete block in the building is hand cast and hand hammered. Certainly the best bannisters in town.