Hi lizdb
The quotes about John come from a Google Books search for "Edith Sitwell" "John Robins" and appear in a 2011 book entitled Edith Sitwell: Avant garde poet, English genius by Richard Greene.
The first quote I can see is
"In any event, the peace of the summer of 1928 was broken only when the two-year-old daughter of Osbert's servant John Robins pointed her finger at Lady Ida and told her to 'Bugger off.'" - Nice! Middle aged and cantankerous, possibly, if his daughters language is a guide.
The second quote -
"At Renishaw, Edith generally had the company of Osbert, his secretary Lorna Andrade, the cantankerous butler John Robins, and his wife Susan, and whichever servants John Robins had not driven away. In August 1940, David Horner joined the RAF... " so that falls into the 'old and cantankerous' category.
I have emailed the Sitwell Society for any more info, so I am on tenterhooks to see if the facts match
Many thanks
Glen