Brockwell Lido (1936-7) by H.A. Rowbotham and T.L. Smithson of LCC Parks Department Architects. Recently successfully refurbished by Pollard, Thomas and Edwards.
This was a particular highlight of the tour - it looked really lovely, even on an overcast March day, so it must be quite something in the middle of summer.
Photo taken on a walk around Brixton and Herne Hill with the 20th Century Society on 8th March 2008.