I remember the one in Spring Lane Erdington, looking just like that. A school as been built there now.
I too remember the site in Spring Lane and am grateful for the opportunity to reminisce about it, although it didn't look like those photos.
The site comprised some 10 acres of marshy ground bounded by the gardens of Spring Lane to the west, playing fields to the south, a public footpath from Kingsbury Road to Berkswell Road and the gardens of Berkswell Road to the east, and Hartshorne's nurseries in Moor End Lane together with Moat Meadow (which was also known as the "Scout Field" on account of it hosting the scout hut of the 105th Birmingham Moor End scout troop) to the north.
It remained under MOD occupation until the end of national service. For one sunday in 1960 it was opened to the public for the day. The access road was from Spring Lane, where St Barnabas School was later built, lined by demolished blockhouses. This forked into two perimeter roads to either side of two pillboxes. The area contained three gun emplacements, each comprising a circle of concrete inset with three screw fixings for the gun and arcs of ammunition cupboards, and an accompanying ramp into the ground lined with larger stores. There was also a command and control bunker with bars at the windows.
The site was subsequently closed and evacuated, but my friend's garden in Berkswell Road afforded us access through the boundary hedge, and we used to play commandos storming the derelict pillboxes and exploring to our hearts' content. During 1962/3 someone dumped and burned an old Ford Popular on the perimeter road by the nearest pillbox - this provided additional realism for our exploits. My friend subsequently became a colonel in the British Army, so it must have been inspiration for him!
One of the challenges for the site was its drainage. Rainwater run-off from the escarpment of Erdington High Street rises as a spring under the gardens of Fern Road, and is piped through a 3' land drain under the eponymously named Spring Lane. It used to emerge beyond the gardens of Spring Lane as a stream known as Holly Brook, which meandered across the width of Moat Meadow (now the Blossom Hill estate) and under a bridge in the corner of the field. It used to then meander across the site, which had to be conduited before wartime construction could begin. The stream was coursed through a deep channel between Hartshorne's nursertes and the boundary of the site access road, before disappearing iunder a bridge into an underground culvert. Run-off of water from Hartshorne's nurseries provided an ever-present tinkling waterfall, which was conducted through a series of ditches and bridges into another small underground culvert. The culverts carried the water underground to and around the perimeter of Nocks Brickworks' quarry to emerge under a bridge in Holly Lane. Despite this drainage, the site was bedevilled with treacherous marshy dewponds. The command bunker was almost completely submerged under water, and the below ground ammunitiion stores always had water in them - it was good sport to jump from one roof to another across the watery void below!
During 1963/4 the school was built on the Spring Lane access road, and the site was gradually levelled and incorporated into the adjoining playing fields during the remainder of the 1960s and early 1970s.
