[rwmj]

My physics teacher in the 1980s (sadly RIP a few years ago[1]) told me that the location of telephone exchanges was a UK state secret. The theory was that the Russians would nuke them destroying the country's ability to communicate, but as their location was a secret that outcome could be prevented. 40+ years on, I wonder if any of that was actually true?

[1] https://johnchess.blogspot.com/2019/11/david-welch-1945-2019...

[JdeBP]

In hindsight, that does seem a little ridiculous; yet it was indeed the thinking. One could see where the exchanges were by simple dint of visiting a place. Soviet spies would just have had to walk around a bit.

Of course, nuclear weapons wouldn't even have had to specifically target exchanges in order to disrupt electronic communications as they already were by the 1980s.

It was amusing to learn a decade ago that the U.S.S.R. military had far more complete maps of many parts of the U.K. than Ordnance Survey published. Apparently down to Soviet spies just walking around a bit, playing tourist.

[ajb]

U.S.S.R. military had far more complete maps of many parts of the U.K. than Ordnance Survey published.

Although amusing, note that its than the Ordnance Survey published. I.E. they had the data, it was just classified. Also, it's fairly clear that the Soviet maps were mostly derived from OS maps. Looking at my street, for example, they have it in a pre-WWII configuration which they could only have got by starting from a rather old OS map. So they clearly only checked for differences in areas they thought important, such as government or military areas - they didn't have people mapping the whole UK. Still it's probably true that one can get more information about certain areas in these Soviet maps than in extant OS maps.

[qingcharles]

I looked up the local telephone exchange on this site for the town where I grew up. It's a big building. I went past it thousands of times and never knew what it was. It can't have been auspiciously labeled in any way or I would have poked around as a curious geeky kid.

[logifail]

> the location of telephone exchanges was a UK state secret

I found myself wondering whether the locations of electricty substations powering critical infrastructure might count as "secret", for instance the three[0] substations that power Heathrow Airport.

Obviously one of them isn't secret any more more, having gone up in flames rather spectacularly on 21 March 2025.

[0] "Heathrow relies on three electricity substations" https://www.bbc.com/news/articles/c6283577llqo

[toyg]

The dullness is eerily consistent. Even in the age of privatisation, when everything is a brand, these buildings are devoid of markings. So it might well be true, we just stopped worrying about it once the cold war was officially over (once we realized the Russians already knew everything they needed anyway).

[snthd]

>As our [1978] trial started, witness after witness from security sites tried to claim that openly published information was in fact secret. In a typical interchange, one Sigint unit chief was shown a road sign outside his base:

> Q: Is that the name of your unit?

> A: I cannot answer that question, that is a secret.

> Q: Is that the board which passers-by on the main road see outside your unit’s base?

> A: Yes.

> Q: Read it out to the jury, please.

> A: I cannot do that. It is a secret.

>Official panic set in. The foreign secretary who GCHQ had bullied into having us accused of spying wrote that “almost any accommodation is to be preferred” to allowing our trial to continue. A Ministry of Defense report in September 1978, now released, disclosed that the “prosecuting counsel has come to the view that there have been so many published references to the information Campbell has acquired and the conclusions he has drawn from it that the chances of success with [the collection charge] are not good.”

>My lawyer overheard the exasperated prosecutor saying that he would allow the government to continue with the espionage charge against me “over [his] dead body.” The judge, a no-nonsense Welsh lawyer, was also fed up with the secrecy pantomime. He demanded the government scrap the espionage charges. They did.

GCHQ and Me, My Life Unmasking British Eavesdroppers -- Duncan Campbell

https://theintercept.com/2015/08/03/life-unmasking-british-e...

[edent]

Sort of, yes. https://en.wikipedia.org/wiki/BT_Tower#Secrecy

[biofox]

Two more examples of exchanges that were kept secret:

https://en.wikipedia.org/wiki/Anchor_telephone_exchange

https://en.wikipedia.org/wiki/Guardian_telephone_exchange

[lxgr]

Wait, what? What else were people supposed to assume about the purpose of a huge tower with very noticeable horn antennas (widely used for long-distance phone calls over line-of-sight microwave at the time)?

[razakel]

It also had a restaurant open to the public.

[ta1243]

The one place in London you can't see it

[thorin]

It wasn't very secret, at least for local exchanges as I went into many in the north-east of England with my dad as a kid.