Last month, the National Portrait Gallery unveiled a huge, new portrait of Anna Wintour. Painted by Alex Katz, the celebrated New York Pop portraitist, American Vogue’s scary editor-in-chief is shown with famous helmet bob intact, but minus her trademark dark glasses. The picture depicts Wintour, whose icy blue stare could run a chill through you (she's known as Nuclear Wintour), against a sunny yellow backdrop – which looks like an attempt to raise the temperature of that icicle glare. You pass it as you enter this year’s BP Portrait Award.