As a group member in the UK and also a past employee of AT&T, I've very much enjoyed the recent contributions about "The Big Hole", and it's encouraged me to send Links to information on a Cold War bunker at which I had responsibility for comms (although in emergency service employment rather than AT&T). Built originally as a WW2 Anti-Aircraft Control Centre for the UK Midlands, throughout the 1980s and 1990s it was "County Main" for the West Midlands County. "County Main" was a UK Government Home Office term for the primary "protected accomodation" in each County which (theoretically, at least) would have been manned by emergency service, local authority and other staff in the event of a nuclear conflict, and for many years they were funded by central government under the Civil Defence legislation. They were essentially one step down from the very much larger, deeper buried Regional Seats of Government bunkers. Each County also had a "County Standby"
which were generally insignificant sites such as basements of local authority buildings.
County Mains also acted as a hub for the ECN (Emergency Communications Network) in each County, which when I was first in post was primarily a Telex-type system using Creed mechanical teleprinters. The ECN was separate from the "normal" telephone network, and remained unaffected by the schemes which were (and still are) in place for the removal of service from the majority of telephone users in a crisis. The ECN was later upgraded by the replacement of the Creeds (when Creed could no longer support them, I believe) with monochrome VDUs, Epson dot-matrix printers, and a bespoke message store/router/prioritiser. The ECN message switch also connected the deep bunkers, plus all parts of UKWMO ( the UK Warning & Monitoring Organisation) and a major role was the distribution of radiation readings which originated at the thousands of tiny, 2-person underground bunkers throughout the country manned by the Royal Observer Corps. The ECN also supported a voice
network which used SX2000 switches at County Mains, and much smaller desktop switches at individual sites linked to the hub.
The bunkers also had a Carrier Warning System instrument through which the warning (almost always, but wrongly, called "The Three Minute Warning" in the UK) of a nuclear attack would be distributed.
In anything less than a nuclear war, bunkers of this type became largely redundant because most local authorities had established facilities at their everyday premises from which they intended to manage incidents of virtually any scale. The distribution of the actual telephones themselves connected to each County Main had also remained optimised for a nuclear war, rather than a major peacetime emergency, scenario; in the area surrounding the bunker in the Links below, for instance, each individual local authority had ten lines while the UK's second-largest Police force in the area had only one (to be fair, this situation was slightly alleviated by eventually allowing ECN voice lines to be connected into, for instance, a Police force's own switch, but this of course also brought about resilience issues in the event of failure of those switches). Shortly after the end of the Cold War, the requirement to house ECN hardware in protected accomodation was
withdrawn, and, given the costs of maintaining and heating a normally-unmanned building, this was the beginning of the end for this particular bunker. The SX2000 switches, however, were additionally housed in Rainsford EMP-protected outer cases, which involved the use of a specialist company who normally moved safes for banks to remove the switch from the bunker and install it at it's new location!
The RCA transmitter shown in the one Link was certainly not a standard feature of such bunkers, and had been bought by a previous Chief Emergency Planning Officer with the intention of broadcasting on Medium Wave AM to the local population remaining after a nuclear war! It was far from new when purchased, having already been converted by a radio amateur for "Top band" operation. It never saw any "bunker" use at all, but has now gone back to work in the Amateur service!
I've got quite a lot of material relating to UK bunkers and the comms equipment in them, if any of you have any queries if I can't help you myself I can normally put you in touch with someone who can!
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