[Stuart]

I think the biggest problem that had was Downton got in first - aired in September 2010 with Upstairs Downstairs airing at Christmas.

I think the reason why Downton stopped making episodic series was because that lifestyle of a stately home and plenty of domestic staff had largely disappeared by the time period they'd reached.

It was difficult to continue forward into the 1940s. It would become rather depressing without as much interaction between the staff and the family. The films seem to work well, and are still very enjoyable.