Green’s Dictionary of Slang

1. a sentence of 14 years’ transportation.

1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc.
1833		‘Poll Tomkinson’ in Convivialist in Spedding & Watt (eds) Bawdy Songbooks (2011) IV 14: The swell to the wipe swore hard and fast, / For fourteen penn’orth down Bill was cast.
1860		Hereford Times 6 Oct. 15/3: Them two fellows won’t be long afore they gets fourteen pennorth across the water.
1867		Leeds Times (Yorks) 9 Mar. 6/6: There is order among the convicts, I tell you [...] A man who has his seven penn’orth or his fourteen penn’orth [...] is only used by such men [i.e. those with a life sentence] as a ticket porter.

2. fourteen days in prison.

1898

Hartlepool Mail 26 Feb. 6/4: Fourteen penn'orth, fourteen days imprisonment.