The Merlin Adventure — Chris Wright

The day Daniel Talbot brought home a stuffed duck in a glass case, everyone thought he'd gone out of his mind. Even he had his doubts at times.
"Fancy spending your money on that," his mother scolded him. "You needn't think it's coming into this house, because it isn't!"
When Daniel, Emma, Charlie and Julia, the Four Merlins, set out to sail their model paddle steamer on the old canal, strange and dangerous things start to happen. Then Daniel and Julia make a discovery they want to share with the others.