Titanic: The Downtown connection
Events like the Titanic’s sinking where mass death is the outcome, often provide a handy vehicle for writers to dispose of their unwanted fictional characters.
One of the many links between Downton Abbey and Upstairs Downstairs is that they've both killed off characters from their respective shows in the 1912 disaster.
Indeed, Downton had barely got past the opening credits of the first episode before a flunkey arrived bearing the dreaded telegram informing the cast that the Earl of Grantham had perished on the Titanic, thereby setting off the inheritance battle that kickstarted the series; the poor sod and didn't even make it to the first break.
The original Upstairs Downstairs, always a classier venture, at least had the decency to kill off a major charcter in Lady Marjorie Bellamy, the mistress of Eaton Square.