An enlarged Panther Model 100, the 120 had a reputation for being less reliable with a tendency for rapid clutch wear, problematical roller bearings and heavy oil consumption.

As competitors produced modern designs, Panther ran into trouble obtaining supplies of Burman gearboxes and Lucas Magdynos, so production ceased in 1966 and the company was wound up.

[1] The Panther sloper engine designed by Granville Bradshaw remained unchanged for 25 years and the 650 cc 'heavyweight' had many of the Model 100 components.

[1] The main shaft was redesigned with larger ball journal main bearings, A smaller exhaust valve combined with a larger Amal monobloc carburettor gave the Model 120 28 bhp at 4500 rpm, an increase of 4 bhp over the Model 100.

The Model 120 stayed in production for as long as the supply of spare parts lasted, but they finally ran out in 1966 and the company folded.