Perhaps not the largest and most long-legged individual (a female?) I think this still shows a good primary pattern with large mirror on p10 just visible under p9 and a solid black band on p5. An unstreaked head marked it out immediately from all the argentatus present that still have dirty winter streaking; along with bright bill with extensive gonys reaching the upper mandible and darker yellow-ish iris and red orbital ring (and custard-yellow legs) it was a bit of a stunner amongst the grotty Scots and Scandinavians. Compare with this and this for examples of individuals in similar plumage with similar structure.
Additionally I picked up three colour-ringed Herring Gulls and managed to get all three ring codes, submission via the improved cr website initially suggests two were ringed in north-east Scotland and one by the North Thames gull group, I'll update when I have more details.