A month or so ago we were watching the birds on the feeders in the back garden as part of the RSPB's Big Garden Birdwatch.
When a green, finch sized bird landed on the feeder we were about to tick of Greenfinch when we both decided that actually it was just too green -- the water between the panes of the double glazed kitchen window didn't help the view.
We quickly realised that we weren't looking at a Greenfinch but rather a Siskin -- not something we have ever seen in the garden before (here or in any of the other houses we have lived in). Unfortunately I didn't manage to get a photo but Siskin went on the birdwatching list for the RSPB.
We have seen both the male and a female a few times since but yesterday was the first time I managed to get a photo (I stood still long enough in the more exposed conservatory with better windows for the male to happily feed). Of course when you can see the bird clearly (rather than through smeary windows) it is obviously not a Greenfinch.