Over the weekend the Australian X Factor filmed a segment of the the show in London. Dannii Minogue a judge on the show attended with her co-stars. Simon popped in to see them during filming.
Speaking about Simon's visit to the set, a spokesman for X Factor said: 'X Factor Australia has been filming in London with all their judges and contestants. This was part of that filming process.'
Dannii was formerly a judge on the UK edition of X Factor in 2007.