Who has been the best guest performer so far?
Week 1 :: Leon Jackson - 'Don't Call This Love'
Week 2 :: Girls Aloud - 'The Promise'
Week 4 : Will Young - 'Grace'
Week 5 :: Mariah Carey - 'I Stay In Love'
Week 6 :: Leona Lewis - 'Run'
Week 7 :: Take That - 'Greatest Day'
Week 7 :: Same Difference - 'We R One'
Week 7 :: Rhydian Roberts - 'Impossible Dream'