Subterranean Stuff

This page contains a fairly random collection of items: mainly images that I've referred to over the years in Usenet articles etc.

An old country pile at Brogyntyn, near Oswestry, has some odd-looking grey bricks in its basement windows. Is this an old BT emergency control centre? Are these bricks the fabled GPO fallout protection bricks?
A scan of a drawing from Turley, T.G., Cabling Problems in Subways and Tunnels, IPOEE Printed Paper No. 187, showing the layout of BT's WWII cable tunnel between Holborn and Faraday exchanges in London.
The Chrysler air-raid siren. This screenshot came from a Discovery Channel showing of a BBC documentary made by Robbie Coltrane about the history of the V8 engine. The siren was powered by one.
A full-page ad placed by the Home Office in The Times on 17^th September 1963, to advertise its civil defence preparations. (Large, 712 KB.)
Front page story from The Observer, dated 18^th August 1985: How MI5 vets BBC staff
Newspaper cutting from The Observer, dated 20^th October 1985: BBC maps out wartime role
Photo of the new shafthead building for the southern end of the Whitehall BT cable tunnel in Monck Street, London SW1, where it used to serve the bunkers known as the Rotundas, which have now been demolished. The building is the anonymous concrete cube with the blue door in the middle.
A list of articles of possible interest from (mainly) The Post Office Electrical Engineers' Journal