TV bosses have renewed Downton Abbey for a fifth season. The fourth season finale of the award-winning period drama, created by Julian Fellowes, aired in the U.K. on Sunday (10Nov13), and seconds after the credits, fans were treated to the good news that the show will be back next year (14). Downton has garnered an average of 11.8 million viewers, becoming the highest-rated drama in the U.K. this year (13). The show is also a big hit in America, but fans there will have until the new year for the fourth season to debut on 5 January (14). The season four Christmas special, which will air on Christmas Day (25Dec13) in Britain, will feature two veteran American actors - Shirley MacLaine, who will reprise her role as Martha Levinson, and Golden Globe-winner Paul Giamatti, who will join the cast as family matriarch Cora Crawley’s playboy brother, Harold.