English guitar by da Silva, Jaco Vieira, made ca. 1780. Museum Number 208-1882. V&A Collection.

The English guitar was a fashionable instrument from about 1750, considered easy to play and tuned in C major, although the player would use a capo, much like a modern folk-guitarist, in order to change the key. The tuning pegs were often small metallic pins that could be turned with a watch-key, to keep the strings in tune longer. This instrument was made in Portugal, a country with strong trading links with England, and its peg box is decorated with a paper 'cameo' in imitation of a jasper ware medallion, a motif made popular by Josiah Wedgwood (1730-1795) from about 1770.
http://collections.vam.ac.uk/item/O92582/english-guitar-da-silva-jaco/