Southwyck House on the other hand is a blunder of a building that is often mistaken for Brixton prison. Known locally as the Barrier Block, it presents a daunting edifice, with early seventies, neobrutalist-inspired architecture and tiny turret windows peering out over Brixton. It was designed as part of the 1968 “box of motorways” project which, had it got off the ground, would have seen a raised six-lane motorway scythe through Brixton. The Barrier Block was designed to protect the Somerleyton estate from the inevitable pollution and traffic noise, which explains its tiny windows and unusual zig-zag design – intended to “bounce” the sound back to the ground. The road project was finally abandoned, but Brixton has been left with this ugly and impractical building...
...Blunder
Southwyck House, a block of flats in Brixton, south London, was built by the Greater London council as part of a wider development strategy that was subsequently abandoned. It has caused controversy since its opening in 1982 – local folklore claims it was built “the wrong way around”. The contractor was Amec Building, Ted Hollamby was the chief architect.
http://www.building.co.uk/comment/wonders-and-blunders/3142026.article