A couple of weeks ago I reported birdsong on a slate bank covered in
mosses, heathers and ferns, just outside my kitchen window here in a
remote valley in West Wales at 7.30 at night (pitch black - sun setting
at 5'ish).  It has happened again tonight at the same time (7.30).  (I
switched off the kitchen light, and scanned the bank with a torch but
could find nothing.)

Anyway, this time I was able to pay greater attention to the call.

It is "wh-ic! wh-ic! wh-ic!".

Any more ideas? - gratefully received, thanks.

Nell.