The Dubliners recorded this too, 1966, and credited to Glyn Hughes.

If Seth was an emancipated Jamaican slave he would have been quite an old one, the Jamaican Emancipation Proclamation of 1834 freed all slaves then aged 6 or less immediately, and all others with effect from 1838.

The UK Slavery Abolition Act came in at the same time, though in the States slavery lasted rather longer.

I have a dancing doll which I suspect was made from a turned table leg or similar, it was given to a relative when he was a child in India around 1910. His decoration suggests 19th century army uniform, except for an earring and a bare midrif. He's a bit of a puzzle really, but it seems clear that such dolls were been around in "Empire" circles at the time in question.