Green’s Dictionary of Slang

penn’orth of bread n.

the head.

1880		D.W. Barrett Life and Work among Navvies 43: When a man is ready to retire to rest, he will inform his mates, ‘That he’s done his lot for the day, and is goin’ to lay his pen’oth o’ bread (head) on the weeping-willow (pillow), and do a little bo-peep (sleep)’.
1992		R. Puxley Cockney Rabbit.