Blue dress just kills Bill

It was the little blue dress that Bill Clinton had hoped to forget.

Worn by Monica Lewinsky during one of their White House trysts, the stained garment became a symbol of the former US president's reckless infidelity.

But now a painter has revealed that he worked a sly reference to the dress into Clinton's official portrait, which is hanging in Washington's National Portrait Gallery.

Nelson Shanks's portrait shows the 42nd president leaning against a mantelpiece with an unexplained shadow looming nearby.

Shanks told the Philadelphia Daily News that the shadow was cast by a mannequin wearing a blue dress that he had set up in his studio while working on the portrait.

"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," he said.