In the French original,
Le charretier de "la Providence" (1931).

Variously published in English as:

(i) "The Crime at Lock 14," with "The Shadow on the Courtyard" (1934), and in The Triumph of Inspector Maigret (1934) (trans. Anthony Abbot);

(ii) Maigret Meets a Milord (1963), and with the same title in the omnibus Maigret Meets a Milord (with "Maigret and the Hundred Gibbets" and "Maigret and the Enigmatic Lett"; 1983); and as Lock 14 (2003) (trans. Robert Baldick);
and (iii) The Carter of "La Providence" (trans. David Coward) (2014).

Please distinguish between the stand-alone title Maigret Meets a Milord and the 1983 omnibus of the same name which includes other works.