I've never heard of him named as anything but W. Gordon Smith. The "Gordon" is part of his surname, he was descended from the Gordons of north-east Scotland. There are quite a few Gordon Smiths in the Edinburgh area.

It's a fine song which has become well-established in Scotland. I've never heard the Irish one and I don't know where W. Gordon Smith got the tune. (His daughter Belinda plays the fiddle and I used to play with her a few years ago, but I never asked her for all the details). I believe he entered it for a song competition and came second to something now long forgotten.

I posted an ABC of the way I hear it sung these days round here in thread 30948. It seems to have been mutated a bit from the Irish version.