Good Afternoon,
Thank you for the replies; I have replied to emails.
The workshop is located on the South Coast near Gosport. I did suspect a ML7, I was not sure if it was a Super or not but remembered Dad telling me about his Myford ML7, I think I found the book too.
I do not believe that Dad was a member of a club, most of the people he associated with to do with the Engineering were people he knew from his Dockyard days (Dad was a Naval Architect) and he knew Toolmakers, Fitter and Turners and lots of others he would regularly pick the brains of.
The loco I think is 4.5-inch saddleback "Bodmin", not sure on the pressure testing although knowing Dad, he probably did it himself; he was also a Diver and had access to the relevant air sources, I know he tested other boilers on previous builds (I have a Stephenson's Rocket and a double oscillating steam powered tugboat).
I will go down South in the next week or two and try to get more information/ photos,
Once again thank you, Jon