(If worse, unsharp pictures of this Gull are needed, fell free to ask me)
I dont know if this is your question: it didnt stand out among the other Gulls by size to me.
If you need pictures of all three species together (which would be really exceptional, I agree with Nutcracker), maybe its good to ask BF members from Poland or other Baltic states or the relevant birding sites on the internet?
on Facebook group Western Paleartic Gulls Csaba Barkoczi published a wonderful picture of adult Ichthyaetus yesterday. The Gull was found in Hungary near Szeged. Find him and ask if you want more pictures.