The Gallery of the Royal Watercolour Society and the Royal Society of Painter Printmakers.
Exhibiting contemporary watercolours and original print. Check their web site to make sure an exhibition is running when you visit.
OG&UG: London Blackfriars 0.42km
UG: Southwark 0.53km
UG: Mansion House 0.65km
11am-6pm during exhibitions.
Always check details regarding opening hours, accessibility and pricing before travelling.