Hi Guys
thank you for your help and I understand the driving wheels are 38/40ins, I have a plan of No.22 in the NARROW GAUGE and SHORT LINE GAZZETT
and looking at the LGB mogul it scales out close to No.22 with those large wheels, but I have spent a lot of time comparing simliar angled pictures of No,s 21/22 and No.s 4 to 10 the driving wheels look a lot smaller and D.,S.P&P.R.R. No.71 and others they again have a bigger look to them. Now this all could be an optical illusion, I can't post the pictures but what I have done is mount them together, same size and angle, and e/mail them to you to try and explane what I am seeing.
Michael