According to the book: 香港古樹名木(Hong Kong Old and Valuable Trees), the oldest tree in Hong Kong for 400 years, which is a Camphor Tree located in She Shan Tsuen, people called it 社山神木(She Shan Big Tree).

References:
香港園藝學會, 中國科學院華南植物園. 2006. 香港古樹名木. 1st ed. 香港:天地圖書.(Institute of Horticulture(Hong Kong), South China Botanical Garden-The Chinese Academy of Sciences. 2006. Hong Kong Old and Valuable Trees. 1st ed. Hong Kong:Cosmos Books.)
Hong Kong Old and Valuable Tree. 2013. [ONLINE] Available at: http://ovt.lcsd.gov.hk/ovt/tree.jsp?lang=en&id=1335. [Accessed 17 November 2013].