Charles Bosley was apprenticed in 1725, made free of the Clockmaker's Company on 7 August 1947 and Liveryman on 16 July 1766. He was furthermore the successor to William Kipling (1705-37), a fine maker.
The repoussé is most probably the work of James Wieland, active in Berkley Court in the 1760s, as described in Richard Edgcumbe's The Art of the Gold Chaser in 18th Century London. He furthermore mentions the influence of the renowned enameller and chaser George Michael Moser (see lot 58 in this sale) on Wieland's work, demonstrated by the snake around the thumbpiece.
It appears that the present watch would only be the 11th recorded example of a repoussé work signed J. Wieland, all found on watches by other renowned London makers such as Benjamin Gray, Charles Cabrier and J. Martineau Snr.