Chief Inspector Daye's theories on what happened:
- Someone stole it, either because they wanted it, or for a joke.
- They're pretty flimsy, so possibly someone, such as the gardeners, was rough with it, it broke, and they threw it out to hide what happened. (Unlikely.)
- It blew away. (Unlikely.)
- Food was spilled on it at some point, which attracted raccoons who wanted the food, so they tried to dip it in the pond to wash it--raccoons like to wash their food--but it just fell in. (I'll poke around in the pond later to see if this happened.)