This steam engine was a childhood toy of my next door neighbour's Dad, who recently rediscovered it hibernating in a shed on the Isle of Wight. It belonged to his father before him, but there is some uncertainty as to exactly who machined the original castings. 1898 would be the earliest date of manufacture.
Amazingly, the company that made the engine are still going. Their website informed me that I was about to attempt to clean up a Stuart Turner S50 model mill engine. I bet their server is powered by coal...
The copper and brass parts were soaked in "Rustins Brass and Copper Bath", the steel parts in "Taylor McLure Scale-X", 42% phosphoric acid.
After everything was cleaned up, the boiler housing was resprayed with heat proof paint, and the engine housing sprayed green. The original asbestos boiler insulation has now been replaced with a modern ceramic equivalent.
Online research into the disposal of asbestos unearthed opinions ranging from "If you say the A-word out loud three times, your head will explode!!!!!", to "Nonsense, my wife and I have eaten asbestos flakes for breakfast every single day for the last 700 years!!!!!"