Certainly looks like the belt driven Shorrock C75 that a friend of mine has fitted to his XPAG engined TA.
Judging by the prices asked for Volumex super chargers the Shorrock must be worth £750? The Shorrock is a vane type and relies on total loss oil supply, as I found out in the distant past the vane supercharger can easily be damaged if the oil supply is not right.
Thanks George, the price tag sounds realistic to me though I have no experience of supercharging. I will inform the current owner who is considering putting it on the market.