Very nice pic from my favourite gull spot!
As Jörgen say´s, a good enough michahellis primary pattern on this perhaps not fully adult (darkish smudging on the primary coverts), with a broad dark mark on p5 as well as mirror on p10, good michahellis combo. Mirror on p9 different in both wings and seems to be located on the inner web - as in this argentatus by Hans from the same location:
http://3.bp.blogspot.com/_Rtfsyd8tugY/S ... cflyg6.jpg
and another argentatus by Hans:
http://4.bp.blogspot.com/_Rtfsyd8tugY/S ... cflyg2.jpg
Dangerous as it might be, the grey tone on this gull doesn´t stand out much compared to the nearby argentatus and compared to the left argentatus in the second pic og this gull, the iris and orbital ring colour and shape of it is similar! The broad - in front of the eye, orbital ring in michahellis is not fully developed in some michahlleis at this time of year. However, on my monitor the orbital ring colour of both the mentioned gulls has much yellow admixed
As mentioned - the first pic shows a good enough michahellis structure, even if the head looks relatively smallish ( I know the danger judging from this).
Just goes to show how difficult some of these are - at least when judging from pic. Although I could consider michahellis (perhaps best option), but can argentatus be excluded?
JanJ