Courtesy of Wikipedia:
1983: As passenger numbers grew, a circular satellite pier was added to the terminal building connected to the main terminal by the UK's first automated people mover system. (This replaced the original North pier dating from 1962, and the people mover connecting the main terminal with the satellite pier was subsequently replaced with a walkway and travelators). A second terminal was planned, and construction began on the North Terminal on the land earmarked for a second runway in the draft plan of May 1970. This was the largest construction project south of London in the 1980s, costing £200 million