There are carriages on the Isle of Man still operating built by this company in Birkenhead. I don't know if it has been recorded in Wirral History but in case not I add it now.

http://en.wikipedia.org/wiki/G.F._Milnes_%26_Co.

http://www.nationalarchives.gov.uk/a2a/records.aspx?cat=140-zme&cid=-1#-1

It could be this building
click

Sorry I seem to be way out

A couple more maps which make me think the numbering of buildings altered somewhat between 1874 and 1950's

Funny. My son is called George Milne, he is the fourth generation that we know off. All from Birkenhead. Hmm

Or then again it could be these, which are the ones with the commemorative plaque on the front...

Oh well done - spot on!