These lovely stained glass windows can be found on the upper level of one of the two blocks of flats in the triangle made by Riverside Drive, Hardwicke Road and Cave Road. The window looks out over Riverside Drive where it almost hidden by a large tree.
The stained glass is further hidden in the daytime and is almost invisible unless a light is shining through it from within the block, and that only happens once it starts to get dark. At night the stairwell light does what it is meant to do and illuminates the coloured panels, turning them into something with the geometric feel of a Mondrian painting.
The colouring is only on the top floor and only in the one block so I presume that it is something unofficial done by one of the residents, possibly using materials from the shop Peels of London in Ham Street opposite Grey Court.