For some reason, I haven't been able to find him on the 1939 register. However, he is listed in the 1932 electoral roll at the St Hilda's road address with his first wife, Harriet (nee Dellow), who was a lady's maid. She had also worked at Eden Hall in Kelso. After her death in 1935, he married Annie Johnson, who was working for a different household as a kitchen maid in the 1911 census.
ETD's will was written in 1936, not long after his second marriage, and has the same address. In it, his occupation is butler. When his second wife died in 1979, she still lived at the same address.
I know he had a legacy from an aunt in 1923, which might have enabled him to buy a house.
I've looked at the house in St Hilda's road on Streetview, and it didn't look to me like the sort to require a butler, but I could be wrong. Of course, he might have changed occupations at some point, but he didn't update his will after 1936.
My knowledge of butlers' living situations is, I fear, limited to what I saw on Downton Abbey, which may not be a reliable guide!
I'm told by a young Yorkshire woman that Harrogate could well have provided employment for a number of butlers, being a bit posh.
The 1939 register would help to establish if he and his wife were living there alone or as staff in a larger household. I've looked, but can't find it.