Did they build that many? A quick glance at the LNER Use of Engine Power document for 1942-46 is revealing. What do you define as an "express passenger loco" by 1946 though? Because you would certainly class the Pacifics in mostly that category, some B-types perhaps. By 1942, is a C1 Atlantic an express locomotive anymore? Where do you draw the line? I'd say A10, A3, A4, A1/1, A2/1, A2/2, A2/3 by 1946 - that's only just over 125 locomotives. Everything else - i.e. the other 6300 odd locomotives - is mixed traffic, freight, or shunting types!