What no one noticed about this portrait of Bill Clinton

This official portrait of Bill Clinton was unveiled by the former US president at the Smithsonian in Washington in 2006.

But it's only just emerged that it includes a hidden reference to one of the most notorious episodes of his presidency.

See the shadow on the mantelpiece? Artist Nelson Shanks has revealed that this is a reference to Monica Lewinsky's infamous blue dress.

He told the Philadelphia Daily News:

It actually literally represents a shadow from a blue dress that I had on a mannequin, that I had there while I was painting it, but not when he was there. It is also a bit of a metaphor in that it represents a shadow on the office he held, or on him.

(Pictures: AP/Getty)

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