I spotted an unusual bird this morning. It was feeding with green finches and sparrows. It looked similar colouring to a sparrow but with a white markings on the wings. The face and part of the cap are white and the beak is different to a sparrow, more similar to a robin in shape. I thought it could be a tree sparrow but I don't think the markings are correct. I live in the Western Isles of Scotland. Can anyone help identify it please? Thank you in anticipation.http://flic.kr/p/94yRrV