In 1985, Ian Mikardo MP announced he was standing down for the coming election. His local party in Bow and Poplar needed to select a new candidate for the next election and, in their process of selection, had two likely names to choose from - John McDonnell (former Chair of Finance at the GLC) and Mildred Gordon (a former local councillor and member of the executive of the London Labour Party). Mildred Gordon was picked IOTL and went on to win in 1987.
What if John McDonnell had been selected and had arrived in Parliament a whole decade earlier than OTL?