Master impressionists Jon Culshaw and Debra Stephenson bring a whole host of celebrities with a festive twist, in the last show of the series. Katherine Jenkins and friends sing the Christmas No. 1s, with Liza Minnelli and Amy Winehouse popping up for special appearances. Elsewhere, Lady Gaga is forced to leave a party early when she realises her outfit isn't unique; and Julie Walters and Richard Wilson appear in a Dickens drama. Ian Hislop meets Santa and old favourite Ross Kemp investigates a gang who run a seasonal extortion racket. Meanwhile, Simon helps Cheryl with her texting etiquette - just how many kisses is it polite to sign off with?!