Number 4, Christian Street, according to G.W. Lockhart's biography "On the Trail of Robert Service". Nice to know he's got a blue plaque!
Read the book at
https://books.google.co.uk/books?id=fNJqjffQjYQC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Ross