ATC history
After the war the military still retained control over the UK airspace.
When commercial aviation got back on its legs the ATC responsibilities were shared between the two. But with the military still flying the greater number of aircraft, the civilians took back seat.
However, the number of air-misses between largley unregulated military aircraft and the civies resulted in letters to the air ministry complaining about them. In a short while the commercial aircraft operating in and out of the london area was greater than the military and after many furious arguments it was agreed that a civilian ATC system would be the controlling authority for the new Metropoliton Control Zone.
An operations room was needed and an old hut about 60 ft long by 30 foot was found in the grounds of Hillingdon House . However it tilted down on one side and three old railway sleepers were used to raise it on one side. That was why it was called the "Listed Building"
The Centre was divided into north and south with dedicated controllers on raised platforms, with a military liaision officer down the end. The controller in the middle comunicated clearances given by the controllers to the various airfields within or just outside the Zone.
Initially, the Zone only came into force during IFR.
All the best.
xpz67
xpz67