Five minutes on Google tells me it is a Grade II listed building, completed in 1969. Lionel Bret, the design company’s chief architect, was President of the Royal Institute of British Architects in the 1960s. It won a RIBA prize on opening.
It has 11 floors and “was an outstanding building in its day for its bold use of square boxed bronze framing and all darkened bronze glass walls suspended on an internal steel and concrete skeleton”. Nice, but the walls are thin and it’s gloomy when the sky darkens.