Looking for a 1981 London Marathon finisher’s medal

Hello all, this is a long shot, so bear with me... one of the members of my running club is a London Marathon Ever Present. Sunday would have been his 40th race and he’s still committed to finishing in October (or whenever it is). He lost his first ever medal from 1981, and would love to replace it. Can anyone out there help? It would be amazing if someone could. Happy running and stay well.