Den hollandske mågeekspert Peter Adriaens har været så venlig at kommentere på billederne af "Svalbard Gull".
I agree with you that this looks like an interesting bird, with the potential of being a smithsonianus. The paleness of the greater coverts could be due to wear and fading.
However, unfortunate as it may be, the photographs just do not provide enough detail to be sure...
Various problems should be taken into account:
Older immature smithsonianus are not an easy plumage to identify, especially in summer when wear and fading may suppress some important features.
Also, many immature European Herring Gulls, especially those from Iceland and the Faroes, may look deceptively similar to smithsonianus.
It is therefore very important to study the exact details, such as uniformity of the underparts, uniformity of hindneck, exact pattern on vent and undertail coverts, and pattern of wing coverts, and I find this impossible to do in your set of photos.
The tail pattern alone - even though it looks spot on - is not enough, and neither is the few dark markings on uppertail coverts.
See this 2w Herring Gull, e.g.:
Sorry to be of little help!Peter