Londoners were left shocked after a prank video released by Sky 1 brought an imaginary friend of a passer-by to life right before their very eyes.

Commuters and day-trippers in the capital were left confused and surprised as they were approached by a young man, standing alone, asking them to take a picture of him and his 'friend' Mike. Unsuspecting pedestrians were baffled as the resulting photo showed there were in fact two men in shot and not one.

The clever prank was performed to celebrate the launch of the third series of Sky 1's comedy series Moone Boy, which tells the story of a boy and his imaginary friend.

The prank involved rigging a Polaroid camera with a pre-shot picture of the young man and 'Mike'. The camera was modified to eject the pre-shot Polaroid, giving the impression of a newly taken photo. Producers worked through the early hours of the morning to place hidden cameras in strategic locations around the Southbank to capture the best reactions from unwary Londoners.

Matthew Arnold, Marketing Manager, Sky 1 said, "In celebrating Moone Boy's return to Sky 1 on 2 March, we wanted to have a bit of fun with one of the show's central themes – the joy of having a make-believe friend. Tourists and commuters were left baffled and stunned on the discovery that the Polaroid photo they took contained an image of two men rather than one.

"Moone Boy is the story a young boy and his imaginary friend, so we thought this prank was the perfect way to celebrate the launch of series three of the show and connect the public to the life of Martin Moone and his own imaginary friend played by Chris O'Dowd," he added.