Sleep is the Enemy
Conserning Peters gull - well it looks like a heuglini - but which form in Thailand one could ask - could be western heuglini though.
The Dutch Birding bird - is that a gull - looks more like a Tern of some sort.
first of all, your a hard man to get hold of since your PM box is full, i may have clogged it up..
Peters gull: i guess nobody really knows what winters in Thailand but this one looks odd for a Western heuglini, i would not have expected black on p4 but i'm sure one of the GRO members involved with heuglini may be able to shed some light. I still hope that one day some daring soul will start putting colour-rings on chicks but it will be a hell of a job.
I'd say the Dutch Birding bird is not a gull...