Mahogany: a drink for Christmas?

In Thomas Bond’s History of Looe, published in 1823, he talks of the fishermen of Looe drinking a concoction of two parts spirit, (usually gin) and one part black treacle to keep them warm on winter nights. The said drink was called Mahogany, probably due to the dark colour? Bond mentions a witness at the County Assizes telling (and puzzling) the judge by giving an alibi that he had been “eating fair-maids and drinking mahogany” (fair-maids being an old name for cured pilchards).
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It is also known that at a dinner party held at Port Eliot in the mid 1700s, given by the artist Sir Joshua Reynolds, that Lord Eliot had a brew made up of, ‘a curious liquor, peculiar to his country, which the Cornish fishermen drink’, Attending the party was the writer and traveller James Boswell. He later described it as a “very good liquor” comparing it to ‘Athol Porridge’ a Scottish drink of whisky and honey. His friend Johnson stating that the Scottish version must be better as it has better ingredients!.