Hi Zacktyr. Sorry, I don't have any knowledge regarding Barga records. Is it possible, and this is pure speculation on my part, that the groom spent part of his adult life in Glasgow and therefore needed a document to verify that he hadn't married there previously. I know that in the late 19th and early 20th century, lots of Italians went to the UK as ice cream vendors, confectioners, sculptors, street musicians, etc. He might have been employed by someone from his town, or a relative. Even though he was illegitimate, if his mother gave her consent, he must have known his relatives, and maybe one of them took him under his wing and took him to Glasgow to give him employment. I can stare at that word forever, and I still see "Glasgow". The "w" looks exactly like my father, who was educated in Italian, used to write it -- like a double "v". Perhaps if you look up the census for the years he "might" have been in Scotland, who knows, he might show up. Sorry, I can't be of any more help.
Mary