Called in here on way back from the Rhymney for a quick scan from the Ice Rink boardwalk. Got on to a ‘Commic’ Tern feeding with the BH Gulls. Through my mini scope I kind of convinced myself it a an Arctic although Peter Howlett had seen a def Common y’day and poss also this morning. My impression was of very  clean upper wings, slightly dusky belly making white cheeks stand out, and also impression of different flight – wing beats not so deep, slightly more ‘relaxed’. COuldn’t see enough detail to see bill size or colour.