'One's outstanding impression is of the exceptional flexibility and smoothness of the engine – it seems almost incredible that so much docile punch should be the product of no more than one cylinder and an 8.5:1 compression ratio,' enthused Motor Cycling about its test Viper, summarising characteristics that will be familiar to anyone who has ever ridden one of Hall Green's delightful high-camshaft singles.

Engine development pursued as part of the scrambles programme bore fruit in 1956 in the shape of the high-performance 500cc Venom and its 350cc sibling, the Viper. The MSS frame and forks were retained for the newcomers but full-width alloy hubs were adopted to boost braking power and smart chromed mudguards fitted to enhance the models' sporting image. The Viper ceased production in 1968, two years before the Hall Green factory closed forever.

Although this Viper's frame number is visible, the figures are obscured by a combination of rust and old paint and thus are indistinct. There are no documents with this Lot