The introduction purports that this is based upon real events. As it is written with subtle humor, a dab of satire, and a measure of exaggeration, as he essays their experiences enroute up the Thames River. I suppose it might be classified as a fictional travelogue, particularly as the narrator (the author) often treats the dog mentioned in the subtitle as having human qualities, such as speech. I found the first half of the book rather humorous as the author essays around the happenstances of his unwieldy crew. Then I seemed to get bogged down, much like the crew of his boat. The asides are more mundane, less witty, although the trout story near the end brings things back into perspective.
This is an amusing account which provides a bit of British travel history laced with humor.