I found this second-winter Mediterranean Gull at Ferry Meadows CP, Peterborough on 9th November. I could see it was colour-ringed, but couldn't read the ring properly and didn't have a camera. Luckily, today (14th), it was in exactly the same place, resting with Black-headed Gulls on the littel T-shaped pontoon dock outside the watersports centre on Gunwade Lake. And I had a camera! It looks like ASSH to me. Record submitted. I will keep you posted on the bird's provenance.*POST SCRIPT: as you can see from the last picture above, the Med Gull was ringed in souther Sweden (on the Baltic side) in June 2016. Fascinating stuff.