BBC1 has recommissioned revived period drama Upstairs Downstairs, doubling the run to six episodes.

Controller Danny Cohen has ordered a 6 x 60-minute series, which will continue to follow the fortunes of the Holland family as they face social and political upheaval in the late 1930s.

Though cast and production details are still to be confirmed, the BBC said the new series would include “a shocking twist that will turn the world of Upstairs Downstairs as we know it on its head”. Cohen said: “The return of Upstairs Downstairs was well received but what drove us to recommission were the imaginative and distinctive plans the team has to take the drama forward.”

The first run of the revised classic was stripped over three episodes, starting on Boxing Day. It debuted with 7.5 million (28.54%) and peaked with 8.9 million (30%), according to consolidated Barb data.

The revival saw Jean Marsh reprise her role as Rose Buck, but as housekeeper rather than parlour maid. Set in 1936, storylines revolved around the emergence of British fascism and the abdication of King Edward VIII.

Although no date has been set, the second run is scheduled for 2012, meaning it will once again run after ITV1’s Downton Abbey, a second series of which is due to TX this autumn. The Julian Fellowes-penned drama, set shortly before the First World War, opened its seven-part run with 7.68 million (30%) and closed with 10.8 million (36%).