Esquire (Latin, scutarius, shield-bearer) was a personal attendant of a knight, which evolved into an apprentice knight, and later into a lord of a manor. The numbers were swelled by those of the knightly class who did not take up knighthood. By the 14th century an esquire (armiger) practically attained equality with a knight, both in function and privileges. With the rise of the use of the term gentleman as a rank, it became increasingly difficult to know where the lower limit should be drawn.
In Britain the title of Esquire is presently allowed to: the heir male of the younger son of a nobleman, the heir male of a knight, those who by long prescription can show their lineal ancestors were styled as Esquires, sheriff of a county, a Justice of the Peace or those styled in the Sovereign's commission (who cease to hold the title when the office ceases), certain of the Sovereign's servants by reason of the office they bear, such as officers of arms, sergeants at arms, etc., Companions, Commanders, Officers and Members of Orders of Knighthood and Chivalry, Sergeants at law, Queen's Counsel, Deputy Lieutenants and Commissioners of Lieutenancy, Commissioners of the Court of Bankruptcy, Masters of the Supreme Court, Royal Academicians; also persons to whom the Sovereign grants arms with the title of Esquire, persons who are styled Esquires by the Sovereign in their patents, commissions or appointments, and officers of and above the rank of Lieutenant RN, Captain in the Army and Flight Lieutenant.