Green RX02 looked vaguely familiar on reading Liz's post, so I had a look at the 2015 Ceredigion Bird Report and sure enough it was seen at Aberystwyth in August 2015.
For the benefit of anyone who hasn't got a copy of the report, the bird was ringed as a pullus just to the south of Paris in June 2014 and was on the coast near Cadiz, Spain in Dec 2014, on the Brittany coast in April 2015 and inland nearby in May '15.
Of course, it may have been seen locally since then.