Colour-rings applied?

That does help. Eurasian Sparrowhawk. Females (larger than males) very partial to a pigeon.

Amount of feathering on the leg looks ok for Harris Hawk but I don't think that is what it is. Not easy to see colour, but I'd expect some red 'shoulders' on Harris Hawk. Where was this taken? Aside from the seemingly dark head this could be a Sparrowhawk I feel.

Also see this figure from Bancroft 1929 in the SanDiego natural history society transactions

Looks quite long billed, with less sharp gonal angle in your image Scott. Compared to one I photographed in Shetland in July. Possibly aranea rather than nilotica?

That one is a black-headed gull Selv. Note the black in the primaries that an adult Mediterranean Gull would not have

I think you are correct and that's a personal account. As far as I know Fair Isle doesn't have one (yet).