I checked the IOM Census records and www.lawsons.ca and didn't see any Constance Sayle or anyone remotely soundex'ing like Sayle.
I'm unfamiliar with China too BUT I had a Scottish great uncle die in China in 1895. The family memorial stone had three letters after with his name: C.I.M. I researched it quickly on Google and found it stood for the China Inland Mission. This was one of the missionary societies that preached Christianity in China and was based in Shanghai in 1895.
I spent an hour Google'ing the China Inland Mission last week, hoping to find. perhaps, a list of missionaries. I had no success however it seems their archives are held by the University of London but aren't "Internet ready". http://www.soas.ac.uk/library/index.cfm?navid=1402
There's a brief history at http://www.cb.omf.org/content.asp?id=27445