Brown Brothers’ famed traveler’s letter of credit dated to 1824, when the Browns issued a £250 line in favor of John M. Colston of Virginia, who was traveling via Liverpool to see his brother in Paris. Arriving in Liverpool, Colston went to the Browns’ office, letter in hand, where he was able to draw on this line to arrange onward travel to Paris.

This was a convenient alternative to carrying foreign banknotes, but it was limited to the Browns’ Liverpool office. Which is why, in the 1850s, Brown Brothers introduced a “circular” letter of credit, which permitted the traveler to withdraw local currencies at any one of numerous correspondent banks abroad.

The circular letter of credit grew in popularity as more and more Americans traveled to Europe. By the early 20th century, Brown Shipley’s London office in Founder’s Court had come to resemble a private club, with clients dropping in to collect mail, read newspapers, socialize with fellow travelers, or just leave messages before going on to the Continent.

Brown Brothers did not issue a credit to just anyone. As the New York Times explained, a letter of credit had a “confidential character” that required the firm to “be thoroughly acquainted with the standing of the persons to whom they issue their credits” beyond the cash or “sound stocks or bonds” they put up as collateral. The very fact that one carried a letter from Brown Brothers indicated to anyone in the know that the bearer belonged to respectable society.

In time, the circular letter of credit would be eclipsed by the traveler’s check, which did not require a visit to a correspondent bank and was issued in small denominations. In 1947, Brown Brothers Harriman decided to shut down its traveler’s letter of credit business—but not before it had helped build trusted relationships with thousands of private clients and correspondent banks all over the world.