I am a firm believer in Terry Pratchett's assertion that there are wild stories out there just flying around waiting for someone to bump into them. Well, I seem to have bumped into one.
The Book of Waggage is a story for kids about a dog and a small boy who fall into his Dad's rather manky pond and find themselves lost in the time of William the Conqueror surrounded by some very cross Anglo-Saxons, a couple of mad old hermits. a greedy monk, a very large stonemason with a wind problem and the most evil PE teacher in the world.
More info here.