This video from Britain says about itself:
BTO Bird ID – Little Egret and Great White Egret
12 March 2013
25 years ago the sighting of any White Heron in the UK would have been greeted with excitement. While Little Egret is now relatively common, it can sometimes be confused at distance with a much rarer visitor – Great White Egret. This video also helps separate GW Egret from ‘white’ or leucistic Grey Herons.
The birds were counted at the roosts where they sleep. They were over 7,100, a record number. The biggest roost was in Kollumerwaard nature reserve: 352 great egrets.