Following the success of Cats Do Countdown earlier in the year, Jimmy Carr, Sean Lock and Jon Richardson once again take on the famous words and numbers quiz. Jimmy Carr hosts proceedings, and Sean Lock faces Jon Richardson in a rematch of the original encounter. David O'Doherty is in Dictionary Corner along with Countdown regular Susie Dent. Meanwhile the country's favourite boffin Rachel Riley provides the letters and numbers with a little help from comedian Joe Wilkinson. Jon returns victorious from his win early this year. Will Sean be able to even the score or will it be a total whitewash?