Illustrations of Bewick Swans
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Slimbridge swan project celebrates 50th year

11 February 2014 Last updated at 10:47 GMT

Fifty years ago the conservationist Sir Peter Scott made an historic discovery.

While indulging in his passion for painting and sketching Bewick swans, he noticed that each one had a different face.

His artistic endeavour has become one of the world's longest-running research projects.

John Maguire reports.