Green’s Dictionary of Slang

Woolwich pier n.

an ear.

1927		Hartlepool Northern Dly Mail 28 Jan. 5/5: I have also learned [...] that ‘The Duke of Kent’ means rent [...] ‘Charley Prescott’ waistcoat, ‘Woolwich Piers’ ears [...] that a policeman is known as a ‘grass’ — short for grasshopper which rhymes with ‘copper’.
1998		R. Puxley Fresh Rabbit.