knapper’s poll, n. — Green’s Dictionary of Slang

knapper’s poll n.

[nap n.² (1)+ SE poll, the head]

(UK Und.) a sheep’s head.

1703		Hell Upon Earth 5: Knappers Poll, a Sheeps-Head.
c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: Knappers Polls a Sheeps head. Cant .
1788, 1796		Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn).
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.