What is the origin of “A Number One”?

A Number One in the sense of prime, superior or first-rate originated with a symbol used in classifying ships in Lloyd’s Register of British and Foreign Shipping, a yearly publication dealing with the design and construction of vessels of all nations and with data about docks and harbors. Beginning with, its issue of 1775-1776, Lloyd’s Register classified the characteristics and condition of ships by means of letters and figures. The character and condition of the ship’s hull was designated by a letter and that of the equipment by a figure. Thus A-1 (A, hull, and i, equipment) meant that both hull and equipment were in first rate condition. A-2 meant that the hull was first-rate but the equipment second-rate, etc. Some authorities believe that A-1(usually written A Number One or A One) was first applied figuratively to persons and things in general in America and not in England, although that is not certain. It is a common mistake to suppose that Lloyd’s Register of British and Foreign Shipping is published by the famous insurance association known as Lloyd’s. Lloyd’s Register has no financial connection with the insurance association. It is published by a different society and is housed in a different building. Although originally it provided shipping information primarily as a basis for marine insurance, it is now chiefly interested in the improvement, safety, regulation and inspection of shipping. Lloyd’s Register no longer uses A-1 to designate ships with hull and equipment in first-class condition.