This looks really well exposed to me Will. You've got some detail visible in the blacks of the head and nice shades of grey under the wing and across the back and still some detail in the bright whites of the outer wings. This back pedalling archangel wing formation is one of my favourites with these big winged white waterfowl. And I like the flared translucence of the tail. This looks like it must have been a fairly diffuse light?
Beautiful, light and airy. As Bob mentioned, there is a lovely translucent light. Often with terns, it seems the eye is not clearly visible, but you have managed that which is a huge bonus for me.