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].