The one for me was last winter, just after christmas. It was during the snowy period, i was on my local patch and had managed to track down a pair of Bullfinch by their calls. Over the space of half an hour i followed them around feeding, at times the male and female where both on the same plant(old thisle heads) would have made fantasic pictures, especially as it was totally snow covered ground and it made the Bullfinch look very bright
