How Tom Beat Captain Najork and His Hired Sportsmen (Children's book, 1974)
Tom is so good at fooling around that he does little else. His Aunt Fidget Wonkham-Strong, who thinks this is too much like having fun, calls upon the fearsome Captain Najork and his hired sportsmen to teach him a lesson. So the Captain challenges Tom to three rounds womble, muck, and sneedball, certain that he will win. However, when it comes to fooling around, Tom doesn't fool around, and his skills prove so polished that the results of the contest are completely unexpected...
Review quotes:
"The partnership between author and illustrator is almost perfect, their resourcefulness in making such absurdity so natural almost the equal of the boy Tom in his creation of the two-seater, jam-powered frog." The Times (from the Amazon.co.uk product description)
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