Brilliant Corners...Great sound system, vinyl only, dancing, left field, fourth world, jazz, afro, and some refreshing cocktails to help with all the sweating. Probably the only place i will actually dance in.
They also do amazing Japanese food earlier in the evening.
Free natural ponds, open all year round (check online for varying opening hours according to seasons). Get an absolute get away feeling right in the heart of London, a treat if you enjoy swimming with ducks. Amazing park to enjoy a few games of cards and a walk around afterward too...