Riddle of the garden eggs

We’ve been receiving puzzling reports of strange egg sightings. Large eggs have been discovered, often half-buried, in gardens and tree pits. They are unmarked and the size of large chicken eggs, or possibly duck eggs. The one pictured here appeared overnight in a plant pot in a basement area. It lay there for about three weeks before disappearing.

(The thought that they might be duck eggs arose after a neighbour in Arlington Square found a duck’s nest with 10 eggs – 40ft up on his roof ! Once the ducklings had hatched, but before they could attempt to fly off from their four storey-high home, they were gently taken down and set free beside the canal.)

Are these latest arrivals duck or hen eggs? Where do they come from? And who has been taking them and storing them in the ground? It’s rather early for the Easter Bunny. Surely they’re too big for a squirrel to carry? Is it the work of our local foxes? Even stoats from the canal have been accused. Any theories gratefully received.