Louis Walsh has been heaping the praise on Katy Perry, saying that the ‘California Girls’ singer was ‘fantastic’ in Dublin this week.

Katy was the third guest judge to join the X Factor auditions. Geri Halliwell previously stepped in for the Glasgow show and Australian pop star Natalie Imbruglia filled Dannii Minogue’s seat in Birmingham.

However, speaking to the Evening Herald, Louis Walsh admitted that Perry has been his favourite Minogue replacement so far. He said:

‘She was fantastic, she was one of the best guest judges we’ve ever had.’

Pixie Lott will be sitting beside Simon Cowell and Cheryl Cole at tomorrow’s Cardiff auditions while Pussycat Doll star Nicole Scherzinger will be at the three Manchester dates later this month.