"Surely the songster was westering home to Islay from the Scottish mainland?" - Boab

Chorus
Westering home, and a song in the air,
Light in the eye, and it's goodbye to care.
Laughter o' love, and a welcoming there,
Isle of my heart, my own one.

First Verse
Tell me o' lands o' the Orient gay,
Speak o' the riches and joys o' Cathay;
Eh, but it's grand to be wakin' ilk day
To find yourself nearer to Isla.

All of which suggests to me is that this is a sailor born on Islay sailing home from the Far East, most likely on a "Clipper" on the China run.