The Slade Green HAA site (also known as ZS1) was the most easterly anti-aircraft site built inside the London Inner Artillery Zone. Dating back to the late 1930’s, it was possibly built as a prototype to be used as a last resort should any aircraft have passed by the other defences along the river Thames. The site today is in a great condition thanks to locals who successfully campaigned to get it listed – it’s now Grade II listed by Historic England. Still surviving is its core structures including a command post, gun emplacements, air raid shelter and perimeter defences. The four gun emplacement would have been armed with 4.5 inch guns and in one of the emplacements a metal sight, which is mounted between a pair of lockers, still survives and it’s thought to be the only emplacement with this feature. Camouflage fixings can be seen on the walls. In the centre lies the command post building, with an extension added to the north-east, presumably for an LAA LMG for proximity defence or radar. An original metal plotting table remains inside although at time of visiting the rooms were flooded and this was not visible.
Two type 24 pillboxes, to the NE and SE, still remain. Also, to the NW is the slight remains of a rare LAA Bofors gun pit, with only the earthen outline and some brick sidings visible. An air-raid shelter also survives, built of brick and reinforced concrete. There’s two unusual diamond-shaped openings in the shelter, to let light into each entrance-way.