Green’s Dictionary of Slang

a generic nickname for any Welshman.

1617		J. Taylor ‘Iacke a Lent’ in Works (1869) I 117: One that dares take Davy Ap Diggon or Shon Ap Morgan, by the nose.
c.1658		‘Power of the Sword’ in Ebsworth Merry Drollery Compleat (1875) 126: The sword prevails so highly in Wales too, / Shinkin ap Powel cries, and swears Cuts-plutter-nails.
c.1661		‘A Beggar I’ll Be’ in Farmer Musa Pedestris (1896) 27: With Shinkin ap Morgan, with blue-cap or Teague, / We into no Covenant enter, nor League.
1691		‘Country-Man’s Kalendar’ in Ebsworth Bagford Ballads (1878) I 187: Saint Taffie this year, in March will appear, / Drest in hur best Shacket, with leek in hur Ear: / [...] / At every Corner hur Cousin her sees, / Honest Shinkin.
c.1709		Taffy’s Progress to London 5: Hur has [...] two Shild, one call him plack Shack, the othee little ap Shinkin ap Shone.
1719		in D’Urfey Pills to Purge Melancholy V 71: Both Dutchmen and Scotchmen to London did ride, / With Shonny-ap-Morgan, and Thousands beside. [Ibid.] II 78: Shone ap Shinkin Rice ap Tavy, / Shentlemen kindred aw come away.
c.1720		‘Original Black Joke. Sent from Dublin’ 🎵 Then Shonup a Morgan from Holly-head / Was stark staring mad for to go to bed.
1798		‘The Sharps & Flats of the Nation’ in Hilaria 41: Now Sir Watkin ap Williams ap Wynne, / Who came from whence came John ap Morgan.
1884		Leics. Chron. 17 May 12/1: Poor Shenkin went speeding as if the Old Shaver were close at his heels.