I recently had a birdstrike on final, which made a serious dent in the wing. Continued the landing, did report "PH-XXX, birdstrike, landing" but never declared a pan or mayday. Nevertheless, collecting the paperwork and writing down a statement for the authorities took the better part of three hours.
So I guess it's the incident/accident that counts, not whether you've actually declared a pan or anything else.
(This was in the Netherlands though. It may be different in the UK.)