Peter Adriaens (Belgium)
Ies Meulmeester (Netherlands)
Larus cachinnans 2P55 3CY, December 18 2015, Jakuševec-Zagreb, Croatia. Picture: ringing team Luka Jurinovic.
Red 2P55, ringed as chick in 2013 Wytyckie Lake, Poland.
Still brown on several coverts, and medial band on P10 quite broad (but may change with age).