I presented myself at so-called Caperwatch this morning bright and early to enquire as to The Truth. Apparently one brief sighting on the 2nd April has been the ONLY one this year. I for one won't be wasting any more mornings going back.
I also learned something else from the staff member present. Apparently if news of a caper gets out and birders start to know where one is, the RSPB catch the bird and move it tens of miles to another part of the species 'range. This isn't an unsubstantiated rumour or hearsay. A uniformed RSPB employee told us about how daunting it was to try to capture birds; when asked why the Royal Society for the Prevention of Birding did this, he gave the answer above.
I always knew the RSPB disliked birders, and does everything it can to prevent us following our hobby (after all, families with screaming kids pay more). I didn't realise they hate us enough to move a declining Schedule 1 bird from its chosen territory, which presumably the bird itself judges suitable, to another area which they guess may contain what a caper requires, if it can manage to get a territory in edgeways...