Riverside Walk Gardens, Millbank SW1

Locking Pieces is unmistakably by Henry Moore. Created in 1963, this version was presented by the sculptor to the Tate in 1978, who lent it to Westminster City Council to enliven a rather dreary triangle of riverside embankment created by the way the street has to veer inland to allow room for the roundabout at the end of Vauxhall Bridge.
Here's what Moore himself said to Alan Wilkinson in 1980:
"At one time I was playing with a couple of pebbles that I’d picked up, because behind my far field is a gravel pit and there are thousands of shapes and forms and one only has to go out there and I can find twenty new little ideas if I wish, immediately. Anyhow, I was playing with two pebbles which I found like that and somehow or other they got locked together and I couldn’t get them undone and I wondered how they got into position and it was like a clenched fist being tightly … Anyhow, eventually I did get it to [separate]; by turning and lifting, one piece came off the other. This gave one the idea of making two forms which would do that and later I called it ‘Locking Piece’ because they lock together."

I like the simple, unpretentious language, that of a child almost. So much more direct than the art-speak used by many graduates of university art departments.