He mentions that he had served "upwards of twenty eight years" in the Navy, and that his father had died Purser of the Royal Katherine.
The suggestion that Swaine may have been a pupil of Charles Brooking can be dismissed, as the difference in age between the two painters was a mere two years, and there is no visual evidence to support any such influence.
On the other hand, Swaine was demonstrably strongly influenced by the style of the painter Peter Monamy (1681–1749), whose pupil he was.
In Mark Noble's Biographical History of England, 1806, under the entry for Monamy, it is also stated that "Swaine, of Stretton Ground, Westminster, his disciple, and bred under him, was an excellent painter of moon-light pieces."
This remark is well confirmed by his "Capture of the Foudroyant" (see illustration), which is also referred to in at least one source (David Erskine) as "The Moonlight Battle".