LONDON — There’s a dead rat at the heart of a new exhibition mounted by Sotheby’s.

Stuffed and sporting a backpack and a spray can, the rodent is the creation-cum-alter ego of Banksy, the street artist turned art-world superstar.

It’s a sign of his status that Sotheby’s is behind one of the largest-ever Banksy exhibitions, a display of kissing policemen, placard-wearing chimpanzees and smiley-faced riot police spanning much of the artist’s career. Some of the works originally sold for as little as $84. Now prices range from $6,700 to more than $840,000.

Banksy is not involved in the show, which is being billed as an “unauthorized retrospective.” It has been assembled by his former agent Steve Lazarides, who first met Banksy in the 1990s in their hometown of Bristol, England.

The 70 paintings, prints and sculptures display Banksy’s subversive – if not always subtle – humor: Winston Churchill has a Mohawk haircut; a ballerina breathes through a gas mask; a child with an empty bowl wears a Burger King hat.