Hello gereon! You do have some interesting people to chase up! Yes, that's a direct quote - I've just gone back and put quotation marks around it (should have done so originally). To find it, I just went to the 'search' section of
http://www.nationalarchives.gov.uk/entered
campbell mcallum
in the search box and that's one of the two entries (the other irrelevant) which appeared. I should also have entered (and have now) the reference given i.e. the Nat Arch catalogue.
It's interesting that his death was registered under his birth name (though the death notice which you've quoted elsewhere has him as Campbell). Who was the informant? I am wondering whether it was a family member who had grown up with him and knew him only by his birth name. Or perhaps who didn't approve of his change of name
Unlike Lyle, who (if I recall correctly) was thought to have been registered as Eliza - but her death registered as Lyle.
Why would he have changed his name? One thought I had was as follows - Christian was almost without exception a
female given name (particularly in Scotland) in earlier days. And, in the 1800s, many females christened Christian morphed into Christina during their lifetimes. Perhaps he just wanted a first name which couldn't be confusing.
I see you've asked for a 1901 census lookup elsewhere. I guess if he's the chap on the passenger list, he might well have been in China in 1901. Have you found him on earlier censuses?
Regards,
JAP