Go on then, anyone for an educated guess at what made this pellet, and who was on its menu?

(also in the pellet, but not pictured: Lots of grey fur; large fly pieces, robberflies or similar; one small piece of expanded polystyrene). Oh, and no feathers unless I can't see for looking.

It came back from my son's camping trip to Cuckmere Haven, where there's no shortage of candidates.