I think Kenny was absolutely superb for two years, combining the defensive skills he had had to learn under Ron with his attacking and fine crossing ability (watch those videos, Matty Cash!).
How he never played for England is beyond my understanding.
Two games into the new season (82/3), after a 5-0 thrashing at Goodison, he presumably had a massive fall-out with the manager and never played for us again, joining Forest, at first on loan, then permanently.