Green’s Dictionary of Slang

jem mace n.

the face.

1930		(con. 1910–20s) D. Mackenzie Hell’s Kitchen 119: Jem mace ... face.
1932		‘P.P.’ Rhy. Sl. 7: I’ll plaster yer ‘Jim Mace’ so’s yer ‘one and t’other’ won’t know yer.
1938		L. Ortzen Down Donkey Row 9: ‘Jem Mace’ and ‘deuce and ace’ both refer to the face.
a.1945		L. Payne private coll. n.p.: Face Jem Mace.
1947		Argus *Melbourne) 15 Nov. 7s/2: I simply adore your Jem Mace, your neat little Isuppose and your blonde Barnet Fair.
1960		J. Franklyn Dict. of Rhy. Sl.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1981		P. Wright Cockney Dialect and Sl. 105: Jem Mace ‘face’.
1998		C. Fitzpatrick ‘Gower ’98’ on Sussex University Canoe Club 🌐 So we scooted into Jim Brown, for a ship in full sail and to stuff our Jem Mace with some in the nude.