although Northolt, up the road, is an active airfield, the listed part is, I think, just the Polish memorial which is actually outside the airfield boundary.

There are three buildings Listed at RAF Northolt.

Three buildings at the heart of operations during the Second World War at RAF Northolt have been listed at Grade II

The buildings comprise a C-type hangar, former Squadron Watch office, and former ‘Z’ Sector Operations Block. The hangar was used throughout the Second World War to house Churchill’s personal aircraft in which he flew to many important meetings of the Allied leaders. The Watch office which also served as the Aircraft Readiness room during the Second World War had an undisputed role in the Battle of Britain and was the building from which RAF Northolt’s pilots were scrambled. The Operations Block was the prototype for the ‘Dowding System,’ a method of communication allowing the command chain to communicate to intercept enemy aircraft, the first such system in the world. It was recently named the Sir Keith Park Building in honour of the man who developed the air defence system with Lord Dowding and then ‘fought it’ as the 11 Group commander – the busiest Group throughout the Battle.

https://www.raf.mod.uk/rafnortholt/newsweather/index.cfm?storyid=1B8CBA81-5056-A318-A87A03440EF101D4

Brian