Some time ago I drew a pretty picture depicting a 20 year snapshot of the turbulent seas of large white-headed gull taxonomy (see here). July's British Birds included the most recent gripping installment in the ongoing saga. Collinson et al. explains last year's, pretty uncontroversial, recommendations by the BOURC TSC and, amongst other things: extends the range of 'American Herring Gull' way beyond the nearctic; and reduces a fair few peoples' lists by two or three species. Due to the fact that I was bored whilst listening to this morning's cricket, I have redrawn my original flow diagram. I look forward to the day when this step-by-step process results in a frieze extending right round my study, how jolly nice that will look. Interior decor by taxonomists, surely the last word in birding chic.
PS. The asterisk is there to highlight the fact that taimyrensis may actually be best lumped with heuglini or treated as a hybrid between heuglini and vegae; the bold type is there to help you see which taxa have occurred in the UK (I don't think any of the claimed atlantis have yet been accepted, feel free to drop me a comment if you know better).