Raising steam

Welcome to the business end of a half-scale model of a Ruston and Proctor traction engine built by Mike Norfolk of Hove. As part of its regular safety checks it has to undergo a boiler inspection and hydraulic and steam tests. Here it is with a fire in the hole raising steam for the latter having just passed the former.
The working pressure of the engine is 100psi and the steam test involves building a strong fire, running the engine at sufficient throttle to raise the fire radiant heat, run the blower to put even more draught up the chimney and then make sure that the safety valves release the excess steam sufficiently quickly that the boiler pressure does not exceed working pressure + 10% ie 110psi.
I was going to blip that stage of the test but there was far too much steam around and I was too busy so that will have to wait for another year.