commissionaire

One entrusted with a (small) commission, such as an errand; especially, an attendant or subordinate employee in a public office, hotel, etc.

A uniformed doorman.

When the day came Nick turned up early at the bank and waited under a palm tree in the atrium. People hurried in, nodding to the commissionaire, who still wore a tailcoat and a top hat.

An undisclosed agent under European civil law.