Took a look at your map and no 17 used to be no 49.
Addresses have been changed because the late Mr Chan U Seek who owned no 1 Cluny Hill which had a land area
of around 250,000 sq ft had subdivided his land into 1, 3, 5, 5a, 7, 7a, 9 & 9a.
15, 17 & 19 were one plot owned by Straits Steamship...