Every page in the book has artwork that is exactly Irv Spector's wacky style, that you can see in his drawings in his "Muggy-Doo (Boy Cat)" comics, and his "the Farmer's Daughter" Comics, both published by Stanhall Publications, and his "Coogy" newspaper strip. His son, on his "SpectorPhile" at:
irvspector.blogspot.com
where he states that his father wrote and drew all pages in the 4 "Muggy-Doo (Boy Cat)", and 4 "Lucky Duck" books. That was what I've heard for over 50 years, and matches what I see in the artwork. ALL of it looks exactly like Spector's style, and none of it looks like Jack Bradbury's hand. I have never heard that Jack Bradbury had drawn ANY of those books, or seen anything in print saying that he did other than GCD listing Bradbury as the artist followed with a question mark. Spector's son had preliminary art from that series, and, I believe, watched him doing the drawing when he was a child. Maybe GCD should contact Spector's son.
Link to the book:
Lucky Duck 5 (inc)