Green’s Dictionary of Slang

a walk; also as a term of dismissal.

1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 11: Take a pen’orth: Jump one’s bail.
1938		F.D. Sharpe Sharpe of the Flying Squad 329: Pen’orth of Chalk : A walk. ‘He took a pen’orth – when he saw the copper.’.
1957		G. Kersh Fowlers End (2001) 58: ‘Oh, for Christ’s sake, take a pen’orth!’ said Copper Baldwin. ‘Take a ball-o’-chalk!’.
1960		J. Franklyn Dict. of Rhy. Sl.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1984		Partridge DSUE (8th edn) 868/1: late C.19–20.