A 1
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Of the highest qualities. An expression which originated in a practice of underwriters of rating vessels in three classes, —A, B, and C; and these again in ranks numbered.
Abbott A description of a ship as "A 1" amounts to a warranty. Ollive v. Booker, 1 Exch. 423.