My thanks to Richard Thompson for the information.
"I manage an RSPCA wildlife centre and we release back to the wild previously sick, injured and orphaned wildlife, many of which are gulls.
I have released nearly 3,000 gulls over the last 12 years and darvic ringed over 2,000 Larus argentatus, 150 fuscus, 30 marinus and one michahellis.
All birds are released from Pett Level, East Sussex 50:55N. 00:42E.
A6JF, GC69820: This bird was admitted as a small nestling and was in the centre for 53 days. It was released 3rd August 2009. It has been out now for 96 days.
This is the first time this bird has been seen.
Sorry for the delay in my reply.