University of Bristol – Historical Photographs of China reference number: HR01-041. The two cannons had been in the Chinese state's walled garrison in Kowloon. This enclave was later known as the Kowloon Walled City, a notorious lawless and densely populated area, demolished in 1993. See another view reproduced on page 19 of Crack in the Wall by Jackie Pullinger (Hodder & Stoughton, 1989). The cannon survive. See https://en.wikipedia.org/wiki/Kowloon_Walled_City. See HR01-076.
Mac beside cannon, from old Chinese fort, Kowloon, Hong Kong
Black and white photograph
Archives & Special Collections, SOAS Library, University of London