Pegwell lock up

I had to lock up at Pegwell tonight, it was raining and has been all day so was not necessarily looking forward to it. However on arrival the sound of Sandwich Terns perked me up a little bit. Totals for the evening were;
10 Whimbrel, 380 Sandwich Tern, 15 little Tern, 232 Dunlin, 51 Ringed Plover, 21 Barwits, 36 Shelduck, 1 Greenshank and 14 commic terns.

I'm pretty annoyed with myself for not ID'ing the commics, they had very dark underparts and similarly dark upperparts as well as a dull red bill which I was thinking added up to Arctic but the element of doubt kicked in when I arrived home. Looking in field guides they appeared darker in the field than they should have done for Arctic/Common, best left unidentified but i really hope I have not just turned a blind eye on some Whiskereds, unlikely as it is!