Adult winter graellsii LBBG L-80954, October 22 2001, Westkapelle, the Netherlands.
Probably an adult or near-adult born in Belgium: ringed L-80954 Bruxelles. Note the combination of much black on the bill, white tertials tips confined to the inner webs in the upper tertials and the more adult-like primary pattern, with a large mirror on p10 and a smaller one on p9. Interesting to know the exact age of this bird (data will be published as soon as possible).