Great site, Maurice! Like Sthn Jeff I too enjoyed reading about the Stop Out days. And I was there on that infamous - but rather ezxciting day -when Dugdale 'struck' the ref. 'Struck' maybe not the accurate word. As I recall it: seeing that he was being red-carded Dugdale promptly nutted him with a 'Liverpool kiss'. The ref fell backwards, pole-axed (or possibly kop-axed). Ended Dugdale's career I think. Not sure about the ref's career.
He reacted because he thought he was the only one being sent off, having retaliated. Andy Ven den Ede was the other guilty party. As Maurice noted "Ken was under serious provocation when the incident of his dismissal occurred".