I was privileged to be shown around the Northolt ops room a couple of weeks ago. Its restoration is very much a work in progress. It is under the control of the curator of the 11 gp bunker. The chap in charge of the restoration is extremely knowledgable and keen, and there is a great drive for authenticity: e.g. the wall colours will be as was - dark and light green (in the war the RAF used aircraft camouflage paint), and not the magnolia incorrectly used in the restoration at Duxford.
I recall the restorer saying that the ops room was at one stage relocated to a bank in Ruislip, but this was soon found to be inadequate. Northolt was of course the prototype ops room, created pre-war by Dowding. One point that I had overlooked was that the GPO were intimately involved in all this, as being vital in creating a C2C infrastructure, and what bthey were doing for Dowding was very much at the leading edge of teleoms technology of the time.