Allbeit brief! doubt could get anything conclusive, but i thought i might pop it on.
from 15th october 2007! A long time has passed, but i do remember I was sea watching off penninis on st marys isles of scilly

"like a large tern, appearing pale grey bodied, pale grey wings with a white trailing edge. Very fast and bouyant flight, shearing waves like a shearwater at times, pointed wing tips. Short tail, bill short, appeared dark."