I managed to get to Killough Harbour just before mid-day, and there, right on cue, was IJRR!! Or at least, it was a RR bird with I on the right leg - it flew away out of the harbour as I was trying to read the other ring! 😒
It was the only brent goose seen there, and with the back history and other possible combinations, it really can't have been anything else.
Here's wishing it good speed to catch up with all the rest in Iceland, to give it time to recuperate before the onward journey.