All white herons tend to get called egrets, although (Western) Reef Egrets are sometimes called Reef Herons. The latter species has never occurred in the UK, though there were some dodgy near-claims when unfamiliar juvenile Little Egrets started appearing in the UK. White immature Reef Egrets are indeed similar to juvenile Little Egrets, being similar in size and shape, and with similarly greenish-yellow legs. This bird is clearly an egret and the shortish neck (these things are relative) rules out a dark-billed Great White Egret (which have very long, kinked necks). The thin dark bill rules out Cattle Egret, so we are really left with Little or Reef. The narrow bill and dark grey lores should help to confirm this bird as a juvenile Little Egret.
KEY FEATURES All white plumage Dark bill and bluish lores Yellow-green legs ’Normal’ neck length