Like a Willow Warbler - but why that throat?
QI took this photograph at Loch of Kinnordy RSPB in Angus, and thought at first it was a Willow Warbler, but it was larger and has an indistinct mark on the throat. Art Sangster
AWe think your first instincts were correct – it doesn’t appear white enough underneath for Wood Warbler, and although the wings are long they don’t look long enough for that species, either. The mark on the throat is probably just something the bird has picked up along the way, possibly dirt of some sort on the plumage.