The plastic-roofed 'tube' at the City Road studios that inspired the name of the music show produced for Channel 4 by Tyne Tees. The Tube ran for five series from 1982 to 1987.
Image: The_JPS (John-Paul Stephenson 1999) (CC BY)
http://commons.wikimedia.org/wiki/File:Tube,_Tyne_Tees,_City_Road.jpg