"A small anecdote about the Spey. My late friend Eric Appleton of RR loved the engine, but he allowed it was Rolls-Royce's greatest momument for turning expensive petroleum products into noise."
I think the Dart did it better!
The expert in the States on 1-11s was Arthur Trowbridge if he's still around. He was originally with Hunting and knew everything about them, working as a free lance consultant for the corporate operators. Based in Texas if I remember correctly. He would most certainly have the answers.