It's not just Black-headed Gulls which are colour-ringed.
While out conducting a BTO WeBS count a couple of weeks ago, I noticed a 3rd-winter Great Black-backed Gull with a colour-ring at the Whitehouse Lagoon. The bird had a blue ring which was inscribed with "1EL".
I reported it via www.ring.ac and the European coordinator for large gull colour-ringing passed my sighting to the ringer, Chris Honan, who informed me that this bird was ringed as pullus on Ireland's Eye, off Howth, Co. Dublin on 16.07.2010. My sighting on 15.09.12 was the first sighting of 1EL since it was ringed.