Hi
Many thanks to both of you. This all makes much more sense than my original source. It also ties in with the orion.math.iastate.edu website of standard steam classes which gives 14 x 22 cylinders, BP 180 psi, weight 37t, grate area 14 sq ft and evaporative surface 690 sq ft.
Any information on Nyasaland Railways' numbers?
Thanks again
Richard