Paul Giamatti to Appear on ‘Downton Abbey’

Toby Melville/Reuters Paul Giamatti.

Television’s most popular Yorkshire estate is about to receive another high profile visitor: Paul Giamatti has been cast to appear in the Season 4 finale of “Downton Abbey,” according to a statement released by Carnival Films, ITV and “Masterpiece” on PBS on Monday.

The statement describes Mr. Giamatti’s character Harold as the “maverick, playboy brother” to Elizabeth McGovern’s Cora and predicted that the character, along with Shirley MacLaine’s Martha, will “upset the Grantham’s apple cart.”

Mr. Giamatti has appeared on the small screen a number of times over the course of his career and he won both an Emmy and a Golden Globe for his portrayal of the title role in th HBO mini-series “John Adams.” But this guest spot has the chance to be one of his most-watched television roles: the third season finale of “Downton,” which aired in February on PBS, attracted 8.2 million total viewers, up from the 5.4 million viewers who tuned in to the Season 2 finale.

Season 4 is currently scheduled to begin on PBS on Jan. 5, 2014.