Simon Cowell has been left 'shocked and angry' after it was discovered 'Britain's Got Talent' winner Jules O'Dwyer used a stunt double for her dog Matisse's final act.

Jules O'Dwyer and Matisse

Jules O'Dwyer and Matisse

The 55-year-old contestant was crowned queen of the ITV show on sunday (31.05.15) and took home its £250,000 prize after performing an entertaining routine in which she dressed as a policewoman and chased after Matisse when he stole a string of sausages.

However, speaking on ITV's 'Lorraine' the next morning, Jules confessed the stunt in which Matisse was seen climbing across a tightrope was performed by another dog as the pup is "afraid of heights".

The revelation has left viewers reeling and show boss Simon, 55, has called for an investigation into who is responsible for concealing the dog switch.

A source told The Sun newspaper: "He is shocked and angry. He had no idea.

"He wants to know who is responsible. Heads could roll."

Jules has since insisted she didn't mean to "mislead" the public.

She said: "I'm creating a story. It's the magic of the whole act. It's not that we were trying to mislead people, we were trying to entertain.

"Matisse can do all those things. I chose not to do that on the night because I chose to split the act up so as not to over-work my dogs, so every dog can take a role."

The talent show has also issued a statement saying: "The audience had previously seen from Jules' semi-final routine that she works with a second dog Chase alongside Matisse.

"For the final performance, as Jules has said publicly herself, Chase completed the tightrope walking section of the act."