Susan Boyle is being lined up as a guest of this year’s X Factor, host Dermot O’Leary has said.

Bosses on the ITV1 show apparently want the Britain’s Got Talent singer to mentor finalists in the over-25s group, and perhaps perform alongside them, according to The Sun.

Dermot said: “Who she’s going to duet with – that’s the fun part.”

He admitted he’s a huge fan of the Scottish singer, who came runner-up to dance act Diversity in the competition.

He said: “She was brilliant. I think finishing second was probably the best thing that could have happened to her.”

Dermot also believes that her breakdown was understandable after the immense pressure she had been under.

He said: “I think probably the nerves did get a bit too much for her and she reacted in probably the most rational way – which is the same way I’d react if I was her.”

Dermot also admitted that the X Factor is now under pressure to achieve the ratings success of Britain’s Got Talent, which pulled in 19 million viewers.

He said: “We peaked at 13 million last year so we’ve got to get our act together. I’m sure that I will bump into Piers Morgan who is bound to remind me about it.”

In other X Factor news, it was reported that hundreds of fans were turned away from watching the auditions at London’s ExCel Centre on Monday.

Simon Cowell recently announced that hopefuls would now audition in front of a live audience – a format that has proved popular on Britain’s Got Talent.

But 5,000 fans with tickets were left disappointed as they learned that just 4,000 seats were available at the venue.

A spokesman said: “We send more tickets to make sure it’s full.”