He was a bit old, but I think he was to be a man in his early 50s, so Mitchum fit the bill. With a nickname like Pug, one would assume the man to be shorter, but Mitchum was a big man...at least on the screen.
Loved the series and the books.
When they did the sequel the thought was that Mitchum was getting too old to play that role, but in the public’s mind he was Pug Henry and he did a great job. May have been one of the best roles he ever had.
Evidently you missed it in the book when Pug explained to Pamela his nickname came from the Naval Academy where there was already a "Patrick" Henry and since he was a boxer, "Pug" Henry was hung on him.
He was "Pug"for boxing, not "Pug" for the dog--
BTW read my #87 post for the height issue in casting Bob Mitchum.