The engine doesn't need a huge amount of steam Tommy so there is ample reserve, with the burner on full pelt the safety valve will blow constantly, it's on about 2/3 in this video, the engine uses about 100 ml of water in a 15 minute run and I fill the boiler to 500ml so potentially will run for about 45 minutes with a decent safety margin.
I am surprised Jan that more engines don't have bells as well as whistles - or am I just weird?
The 'magic lamp' Arnold was probably a salad oil pourer in its previous life, it is now in use as the dedicated oiler for this engine and contains a good quantity of light oil. It came of course from a charity shop along with much of the other brass pieces, ie condenser, overflow pot, funnel/bell et al.
Glad you enjoyed the short video.
Dave