Appleford Gull Loafing Site with Iceland's plus interest?

For near 2 hours, Gulls in SW of field viewed from gateway. Distant and half of them out of sight amongst ground undulations. A few exceptionally dark L. B-backs, even when sunlit and temptingly like Baltic Gull (L. f. fuscus), but too far away to confirm although one did have exact same pattern of white on wings as Roger's photographed bird). Perhaps 10's of L.f intermedious and 100+ Dutch 'intergrades' (Darker L. F. graelsii). Plenty of Northern Herring Gull (L. a. argentatus) of all ages and far less 'British' race birds (L.a. argenteus). Minimum of 28 (mainly 1st/2ndW) Common Gulls and perhaps 200 Black-headed (great majority adult). c20 G B-backs of many ages.
1stW uniformly brown plumaged, small sized 'Herring Gull' type - and slightly lighter then all others present - with 'classic' pale edging to resting wing primaries, approaching Thayer's plumage(?).
One large darkish 1stW Herring Gull lacking contrasting paler underparts, but would not stand up; so unable to check rear end.
Buzzard appearance (?) spooked all gulls (1415) giving (at long last) views of juvenile and adult Iceland Gull's ascending steeply - and thus showing upperparts in perfect lighting - to cross road southward to land here - Nowt of interest then seen to 4pm, as large gulls remained behind hedge. Hard work, but rewarding.