Hi Richard
I found the post to which you refer.
http://www.rspb.org.uk/community/placestovisit/rainhammarshes/b/rainhammarshes-blog/archive/2012/07/07/quite-remarkable.aspx
I don't remember seeing it at the time but it is a remarkable looking bird.
I see that Howard Vaughan at Rainham Marshes to whom the photo was sent concluded that it may have been a captive bird which had been fed on a pigmented food to produce the colour. Perhaps the one you saw was something similar.
It would be good if you could get a photo.
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Tony
My Flickr Photostream
On the subject of oddly coloured Magpies, there is a juvenile near Kingston Station that has no white feathers. They are either black or dark blue. I always have the camera but as yet an opportunity has not presented itself.
Unicum arbustum haud alit duos erithacos
(One bush does not shelter two Robins)
Zenodotus (3rd Century B.C.)
Hello Richard R and a warm welcome from me in Scotland. I am at the top of the north coast in Caithness. Hope you enjoy being on here. There will always be a willing person to give a helping hand with questions. You will see lovely photos and follow great threads. We are a friendly, welcoming group of people, so enjoy. Lovely looking bird, most unusual.
Beauty is in the eye of the beholder.