The BT Tower was originally commissioned by the General Post Office (usually known as the GPO) with the primary purpose, initially, to support the microwave aerials then used to carry telecommunications traffic from London to the rest of the country. Construction began in 1961 and was opened by Prime Minister Harold Wilson in October 1965. It was officially opened to the public on 16 May 1966 by Tony Benn and Billy Butlin. As well as the communications equipment there was a souvenir shop and a rotating restaurant on the 34th floor called Top of the Tower and operated by Butlins. It made one revolution every 22 minutes. The main structure is 177 metres (581 ft) high, with a further section of aerial rigging bringing the total height to 191 metres (627 ft)
The photos of the Post Office Tower in 1970 come from Glen F’s amazing Flickr site.