This square and reservoir is known as one of the filming locations for Harry Potter. Harry Potter and the Order of the Phoenix features the square as 12 Grimmauld Place.
Wikipedia https://en.wikipedia.org/wiki/Claremont_Square
Official website http://harrypotter.wikia.com/wiki/Grimmauld_Place
Address Claremont Square, London N1, UK
Coordinates 51°31'52.503" N -0°6'37.277" E
