Thanks, Evertype! My statement was misleading, and I'm sorry about that;
let me set the matter straight.

The information about Mr. Maclean's year of birth came from
Who's Who in Literature,
editor Mark Meredith,
Literary Year Books Press, 1924.
Page 258.
I found it through Google Books,
although it can only be glimpsed in
"snippet" form;
Google Books says the digital photocopy came from
a copy collected by Indiana University.

That 1924 publication also gives Mr. Maclean an address of some sort:

17, Hollingwood Lane,
Bradford,
Yorkshire