penny (a pound), n. — Green’s Dictionary of Slang

penny (a pound) n.

also penny the pound

[rhy. sl.]

the ground.

1930		(con. 1910–20s) D. Mackenzie Hell’s Kitchen 119: Penny a pound [...] the ground.
1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 8: Penny-a-pound: On the ground.
1960		J. Franklyn Dict. Rhy. Sl.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1992		R. Puxley Cockney Rabbit.