[TIGHazard]

Can't remember where I read this but because the tower was instrumental in TV transmission back in the day (it probably still is) is it true its actual physical location was effectively a state secret?

en.wikipedia.org 

Due to its importance to the national communications network, information about the tower was designated an official secret. In 1978, the journalist Duncan Campbell was tried for collecting information about secret locations, and during the trial the judge ordered that the sites could not be identified by name; the tower could only be referred to as 'Location 23'.

It is often said that the tower did not appear on Ordnance Survey maps, despite being a 177-metre (581 ft) tall structure in the middle of central London that was open to the public for about 15 years. However, this is incorrect; the 1:25,000 (published 1971) and 1:10,000 (published 1981) Ordnance Survey maps show the tower. It is also shown in the London A–Z street atlas from 1984.

In February 1993, the MP Kate Hoey used the tower as an example of trivial information being kept officially secret, and joked that she hoped parliamentary privilege allowed her to confirm that the tower existed and to state its street address.