The Paxman company has been instrumental (get it?) in creating revolutionary designs for horns over the past several decades. For example, much of the innovative work for the modern triple horn was done in London through Paxman.
This pre-model 6 is a prototype instrument that wasn't readily available for 30 years. It is in great condition and has excellent valve compression (1.4 across 5 valves!). The horn sits in the key of B flat and has a change valve for high B flat as well as a stopping valve. It is made of an unlacquered yellow brass, with the change valves having mechanical linkage and valves "1,2 and 3" using string linkage. The bell is detachable and the horn comes with a fixed bell hard horn case.