'Downton Abbey' has premiered in the US.

The television drama - about the running of a huge country mansion in Britain in the early 20th century - which stars Dame Maggie Smith and was created by Julian Fellows, began a four episode run last night (09.01.11) on the PBS channel.

Viewers discovered the estate of Lord Grantham (Hugh Bonneville) is left without an heir after his cousin James Crawley and his son Patrick die in the sinking of the ill-fated cruise liner the RMS Titanic.

Maggie - who plays the Dowager Countess of Grantham - must accept social norms in Britain are changing, with the country on the brink of great adjustment ahead of World War I.

It has been the most expensive drama ever filmed in the UK, with an hour of shooting estimated to have cost $1.5 million.

However, it has also been the most successful period drama since 'Brideshead Revisited', with around 10 million people watching every show.

The series was cut from seven episodes in the UK to four for US audiences.

Hugh Bonneville, Elizabeth McGovern and Penelope Wilton also take star turns in 'Downton Abbey'.