If something is A1, it is first class or top quality. The US equivalent is A No.1. The origin is from the Lloyd’s Register, which insures shipping and cargo throughout the world. Ships rated A1 are the most seaworthy and attract the best insurance rates, where A was the highest possible rating for the soundness of a ship’s hull and the number 1 was the highest rating possible for a ship’s storage facilities. The Lloyd’s A1 or first class classification dates from the 1775/76 edition of the Register but the first figurative use of the expression to denote first class or top quality is to be found in Charles Dickens’ Pickwick Papers (1837) when Sam Weller describes someone as a first-rater and Mr. Roker replies, “A1”.