Maurice: Mr. R. M. B., of Bodynfoel [92].
Mawddwy Railway: Opened by the Cambrian Railway Company [131].
McCormick: Mr. [41].
McDonald: Mr. G. C. [118].
Melinyrhyd Gate [97].
Metcalfe: Mr. Richard [58].
Mickleburgh: Mr. C. [7], [51], [52].
Mickleburgh: Mr. W. [51], [52].
Mid-Wales Railway [60], [62], [82], [99], [104].
Mid-Wales Railway: Amalgamation with the Cambrian [128], [129], [130].