Bell pull
One of the jokes in My Particular Friend is that Charlotte House often yells out for the maid or footman rather than use the bell pull, which would communicate to the servants’ hall. But reading The World of Downton Abbey, it mentions that the bell system really didn’t come into vogue until the 1820s.
So I was understandably worried that my joke would be an anachronism, but luckily I found this Gillray cartoon from 1805 showing Company shocked at a lady getting up to ring the bell. Of course, I don’t know for a fact whether No. 3 Royal Crescent had a bell pull system installed. One of the oddities about the homes in the Royal Crescent is that their interiors were all uniquely designed as architect John Wood the Younger could only specify the exterior appearance.
An interesting note in The World of Downton Abbey is that the bell pull system, rather than being representative of servitude, actually freed servants who previously had to wait outside rooms, listening for a summons. Personally I think it just freed them to do other work, but it’s an interesting interpretation.