Now, it’s what you have all been waiting for. The Cast of Shrek The Musical sing ‘I’m A Believer’! This video is exclusive to our Facebook fans for an hour before being released anywhere else. Enjoy! Catch a sneak preview of London’s hottest new musical as leading cast members Nigel Lindsay (Shrek), Richard Blackwood (Donkey), Nigel Harman (Lord Farquaad) and Amanda Holden (Princess Fiona) sing the classic Shrek anthem ‘I’m A Believer’. Featuring exclusive behind the scenes footage.