A spokeswoman for the literary agency Gregory & Company said that Ryan had been frail for some time. He was survived by his wife and three children. According to a biography on the agency's Web site, Ryan developed a life-long fascination with pirates when his family moved to Morocco.
Ryan fought in Asia during World War II, and was often reprimanded for drawing caricatures of his commanding officers. He married in 1950, and, in order to make some money to compliment his salary as a school teacher, he came up with the cartoon character Captain Horatio Pugwash.
In the same year Pugwash appeared in the first edition of the "Eagle" magazine, but it was another six years before Ryan found a company to publish his first Pugwash book. More than 20 more Pugwash books appeared since, but it was through the television series that the character won broad appeal in Britain.
Explaining his character's popularity, Ryan once said: "Pugwash has two qualities which I believe are present in all of us to some degree: Cowardice and Greed. "It is the conflict between these opposing emotions which make the stories work. It may be that the Captain is popular because we all have something in common with him. What would you do if you saw a delicious toffee on the nose of a crocodile?"