I found the reference to “number 16” puzzling, so I asked my British born colleague Beverley Parrish what she thought it might mean, and here is her reply:

”I am pretty certain that Dr Murdo MacDonald-Bayne is referring to a bus number. It’s very British to give one’s bus route such significance. The British double decker bus and what it stands for is quite hard-wired into many people's psyche. I have also heard that people who are just about to die often refer to a method of transport to take them on their final journey. For example they might say "my plane is just departing” or (and this comes from a personal acquaintance) "my boat is ready and my husband is waiting" etc. Often people who are "departing" or "passing over" refer to what is familiar or important to them in everyday life. So rather than this reference being something profound or esoteric, I think it is meant in a mundane or literal sense”.

This route goes into the heart of London, so if he was living or staying in the area at that time, the explanation seems quite plausible.