I've used the date they built a permanent building, according to the club's website. Apparently the building was bombed during the war and demolished by the Japanese, who used the grounds to shape the granite blocks for the war memorial near mt Cameron.
"The School was originally an orphanage in the name of “Le Calvaire” operated under “Sisters of St. Paul de Chartres”. It was completed in late 1907 and opened on 6 January 1908 by the then Governor, Sir Frederick Lugard accompanied by Bishop Pozzoni. During the Japanese Occupation, the site was once used as a police station and a jail.
AAB note:
The three-storey house at No. 11 Yuk Sau Street (毓秀街) was built in circa 1929-1931. A land record during the Japanese Occupation (1941-1945) shows that the property was owned by Leung Shou Yick (梁受益) who used it for residential purposes with the ground floor being utilized as a garage. Since 1962, the house has been owned by a Man family.
