All good analysis and questions, MacNara. First of all, the second picture is just an enlargement from the same group of little birds, so yes, the same little birds as in picture one.
Second, mea culpa, I just wasn't really focusing on the larger gulls and with closer examination and better photos from the next day, I default back to the most common gulls here, Black-headed Gull. Bills are too long for Saunder's and wing pattern is wrong.
Third, good catch on the apparent tail streamers, I hadn't noticed that and it would tend to indicate Tern.
Unfortunately, most of the little birds had migrated on with the few in evidence maintaining too much distance. (The only closer access would be from the water's edge in the village across from where I was. The people there happen to be particularly touchy about outsiders, so I respect them and stay out. A few definite adult Whiskered Tern were flying along with a couple of genuine Saunder's which prompted me to realize my mistake. The small ones from the original post still seem to be smaller even than the Whiskered Tern, but size can be deceiving to judge at distance.
I took the better camera rig on the second trip and have included some shots here, if that is any help.