The winning act on the show featured a dog called Matisse and his owner Jules O'Dwyer performing a series of tricks, including supposedly walking across a tightrope.

After the final aired last month (May15), O'Dwyer admitted that Matisse had not performed on the tightrope and was replaced by a stunt double named Chase, prompting a slew of complaints from disgruntled viewers who felt cheated by the dog swap.

Bosses of British regulatory body The Office of Communications (Ofcom) have now launched an investigation after complaints topped 1,150.

An Ofcom spokesperson says, "We've opened an investigation to determine whether viewers of ITV's Britain's Got Talent final, who may have paid money to vote, were misled about the competition."

Cowell previously said of the controversy, "You've got to own up to your mistakes. The viewers have to trust us and know exactly what goes on. There was definitely no intention from the producers to hide this, that I do know 100 per cent. It wasn't one person saying 'hide the dog', so I welcome any investigation."