[Spencer]

Wouldn't be its first rename. BT was originally Post Office Telephones, so the tower was called Post Office Tower. Obviously it became BT Tower when the company split from the Post Office and became British Telecom.

The abbreviation BT wasn’t really used though until the rebrand with the piper logo in the early 90s. Through the 80s it had the full name of the British Telecom Tower, although often referred to as just the Telecom Tower.