Last seen with a Jay. But whose egg?

Last seen with a Jay. But whose egg?

Observation - Last seen with a Jay. But whose egg? - UK and Ireland. Description: Walking along disturbed a Jay so went over to where he had lifted off from and discovered this egg shell which looks to have been bashed into rather than out of. The egg is about 4cm long.But can anyone identify the likely layer?

Walking along disturbed a Jay so went over to where he had lifted off from and discovered this egg shell which looks to have been bashed into rather than out of. The egg is about 4cm long.But can anyone identify the likely layer?