Text on Flickr:
This house stood in the district of Tsim Cha Tsui, Kowloon, on Chatham Road S., between Prat Ave. and Cameron Rd. View is north, with the Gun Club Barracks in the distance. Marie-Félicité, "Bigsis" and her Amah (Nanny) greet a passerby who looks a lot like Jules. More likely they're seeing him off to work.
Of course, the district looks nothing like this now. The mansion, a double house (note second gate), appears in a 1908 picture of the Observatory, but now it's gone. The name on the near gate pillar (and maybe the far one, too) is "Holyrood," after the Scottish castle.
So if I ever go to the Hong Kong Public Records Office to look them up, I have some names (Semichon, Grandel), dates (1908-1912) and an approximate address to go on.
Probably the house was south of (todays) Prat Avenue. On Gwulo it's "Building on Chatham Road, south of Cameron Road". In the distance, Observatory Villas can be seen.