Who's the mystery man who films at Banksy prank auction?

The art world has been stunned by the latest prank by elusive artist Banksy.

Just as the gavel went down on the £1.04m sale of one of the artist's most famous works, it was shredded by a hidden mechanism inside the picture frame.

The auction house Sotheby's denied any knowledge of the fate of the artwork and said it had "been Banksy'd".

Later, the artist posted a video to his Instagram showing how he had secretly built a shredder inside the frame without the dealer or buyer knowing.

A post with the video said: "A few years ago, I secretly built a shredder into a painting... in case it was ever put up for auction."

The artist's identity is a closely guarded secret but footage from inside the auction house has got reporters talking about the role played by a mystery man in the crowd.

As far as we know, there is only one piece of video footage of the moment of shredding, which was the footage in the "official" stunt video.

By comparing this "official" video with other pictures and videos from inside the room, it appears that the person who filmed for Banksy is clear to see.

We have also seen still images - spotted by Robert Casterline of the US gallery Casterline Goodman - that further point to the mystery man's camera footage being the same footage that appears on Banksy's Instagram.

The other mysterious thing about the man in question is that he appears to be wearing tinted yellow spectacles with a built-in camera.

You can buy very similar glasses advertised as "spy glasses" with "full HD camera" for just £29.99 online.

All of this is of course speculation but when it comes to Banksy, let's face it, everything is.