Unknown Pure White Wading Large Bird

Observation - Unknown Pure White Wading Large Bird - UK and Ireland. Description: You can view a video of the bird here - http://www.youtube.com/watch?v=cnrWzul6sn0 I am posting this again as I have no way of ammending the previous posting of it. Identified as a Grey Heron it was not like any Grey Heron I have ever seen and I have seem

You can view a video of the bird here - http://www.youtube.com/watch?v=cnrWzul6sn0 I am posting this again as I have no way of ammending the previous posting of it. Identified as a Grey Heron it was not like any Grey Heron I have ever seen and I have seem many and close by too. It was about the right size, gait, silhouette etc, and had a darker 'belly' but with NO other visible markings whatsoever. Is it possible that you can have a Grey Heron with no markings? The video appears to bleach out the bird and colour, but the very reason I stopped was that this bird was unusual, as I say I have seen many Herons locally, both in flight, at rest and near and in water.