Thanks for the interest and input all. Martin's Canon seems a decent bit of kit so I'm going with that and, hopefully, will get enough answers to cover. I'll report back after the visit.
The project itself was experimental in 1883 so it's unlikely it was a straight line development from drawing to the finished article so some inaccuracy has to be acceptable and, to be honest, it may not even work but it's worth playing with if only to be different!
Cheers for now
Tony
