Rochester portion, n. — Green’s Dictionary of Slang

Rochester portion n.

[orig. use is in a Kentish pvb; ult. ref. to the forfeiture of land by Henry Wilmot (c.1613–58) (father of the poet John) and the consequent dimunition in his wife’s inheritance]

the vagina, lit. ‘two torn smocks and what Nature gave’ (B.E.).

c.1698		B.E. Dict. Canting Crew n.p.: Rochester-portion two torn Smocks, and what Nature gave.
1725		New Canting Dict.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.