St. Joseph's College Branch School 聖若瑟書院分校 [1917-1930]
The predecessor of La Salle College, the mother school of Bruce Lee.
Built in 1917, now Windsor Mansion 29-31 Chatham Road South (source)
It's the building north of Lyeemoon Villas (see 1920 map). It was demolished together with the villas in 1929/30 to make way for Lyemun Flats.