Green’s Dictionary of Slang

jar of jam n.

[rhy. sl.]

1. a pram.

1992		R. Puxley Cockney Rabbit.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.

2. a tram.

1938		L. Ortzen Down Donkey Row 11: Jar of Jam – Tram.
1992		R. Puxley Cockney Rabbit.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.