8th October: The BT Tower

BT Tower (then Post Office Tower) opened on this date in 1965. Here are 10 things you might not know about the BT Tower:

1. The Telecom Tower has 37 floors and is 177.0 metres (580.7 ft) high to the roof and 191.0 metres (626.6 ft) to the top of the antenna spire.
2. The tower was commissioned by the General Post Office to support the microwave aerials then used to carry telecommunications traffic from London to the rest of the country, as part of the British Telecom microwave network. It replaced a shorter steel lattice tower which had been built on the roof of the neighbouring Museum telephone exchange in the late 1940s to provide a television link between London and Birmingham. This was no longer adequate because the communications system required "line of sight" and taller buildings were being planned which would block that.
3. The tower was designed by the architects of the Ministry of Public Building and Works. The chief architects were Eric Bedford and G. R. Yeats.
4. It is a narrow cylinder for a reason: the building will shift no more than 25 centimetres (10 in) in wind speeds of up to 150 km/h (95 mph). This is a requirement for a building housing communications aerials.
5. The tower was officially opened by the then Prime Minister Harold Wilson on 8 October 1965; and officially opened to the public on 16 May 1966 by Tony Benn and Billy Butlin.
6. Why Billy Butlin? Because Butlin's operated the revolving restaurant there used to be on the top. "Top of the Tower", on the 34th floor, made one revolution every 22 minutes. There were also viewing galleries and a souvenir shop. When Butlins' lease expired in 1980 the restaurant closed "for security reasons", meaning London no longer has a revolving restaurant. There is no public access to the tower any more, either, except for corporate events.
7. An annual race up the stairs of the tower was established and the first race was won by UCL student Alan Green.
8. Despite being visible from anywhere in central London, and being open to the public, the tower was designated an official secret and as such could not appear on Ordnance Survey maps. We weren't officially supposed to know about it until 1993!
9. The BT Tower was given Grade II listed building status in 2003.
10. The tower features in many films and TV shows and has been destroyed a couple of times in fiction. In James Herbert's novel The Fog, a pilot, maddened by the fog, flies a jumbo jet into it, and in The Goodies episode Kitten Kong, it is knocked over by Twinkle the giant kitten.