Thanks for the replies - it is Don Biddle. The red herring was the confusion with Luton's match at Portsmouth - the pictured game was a week earlier at home to Blackpool whose keeper was a young John Burridge. A picture of Don from a Wolves match in 1973 clearly shows the resemblance to the referee of the Luton-Blackpool game:
https://twitter.com/FortheR93378109/status/1151909367404474368/photo/1