As has been worked out the latest mystery official is PW Hayward of Bournemouth who only served one season on the Referees List (1968-1969). However that only tells a small amount of the story. That match profile is the only evidence I've come across of him refereeing a match (Colchester v Stockport) and it's possible he didn't actually take charge of the game as Gordon Hill is also credited as the official. It's therefore possible that he either refereed no games or just a very small number.
Normally that would be the end of a referee's Football League career but Mr. Hayward then reappeared on the Football League linesmen's list in 1969, completing two seasons before finally stepping down in 1971. Until the early 1990s only three referees in the post-war era went back to the line. Quite what happened is a mystery - maybe he had an injury which prevented him refereeing, or he asked to go back on the line?
In the eighties and nineties a PW (Peter?) Hayward was a member of the AFC Bournemouth board - being vice-chairman at one stage. It's possibly a coincidence and they are two people with the same surname and initials from the same town but it may be the man on the Bournemouth board and the referee are the same person. Perhaps bmb with her Bournemouth connections might be able to find out the answer.