From memory Wing and Cublington were pretty much the same option. But they were certainly not a one runway concept. From distant memory they were a two runway concept with capacity to expand to four.
The world then was very different. The Govt/planners owned the slots, no alliances, heavily regulated model. The whole concept of hub and spoke and frequent flier miles really came out of US deregulation at the end of the 70s. It's interesting to speculate on how a third London airport would have panned out but that's like wondering what would have happened if Churchill hadn't come to power in 1940. It's history.