Hi. The full size loco was built for the Paris-Orleans railway so was French and looks like a 4-6-2 wheel arrangement or 231 as the French call it. I cannot find a reference to this particular loco.
As the French are not well known for live steam models it is probably German so possibly made by Marklin or Bing of Nuremberg.
What is the track gauge - measure between the wheel flanges. 45mm ( 1.75 approx) = Gauge 1 and 32mm ( 1.25 in approx) = Gauge 0.
These are common gauges for spirit fired live steam locos like yours and will help in narrowing the search.
It does look like British prototype..And not only is it missing its pilot and pony trucks, it's missing a tender !..
If you don't foresee getting it working again (ugh!) I'd put it on a shelf on a comparable size piece of track, with tender, and scale plastic trucks (just floating/not really attached), as a display...