Episode #1.4 - S1-E4
Factual error: William plays a bit of music on the piano - the tune is called "After You've Gone", and it was written in 1918. This episode is set in 1913.
Episode #1.3 - S1-E3
Factual error: The Turkish character "Kemal Pamuk" is given the surname "Pamuk." However, surnames weren't used in Turkey till mid-thirties. Yes, Pamuk is a real Turkish surname but no Turk would be using surnames in 1912.
Answer: Lord Sinderby purchased the house, furnished and appointed, from someone else, complete with staff that come with the home (some of whom aren't happy to be working for a Jewish family). He bought the title, as well. If the artwork featuring Jesus is valuable, he might keep it. Also interesting, his ancestors Anglicized their name, though he is proudly Jewish.
Michael Albert