What is the meaning of A-1 in idiomatic expressions?

Answer 1

Lloyds of London, the great insurers, rated ships they insured according to condition of both the hull and the superstructure, using the alphanumeric system. A-1 means having the best hull and the best superstructure. By extension, it means "top drawer" or simply "very good."

A-1 means best-of-the-best. Back when telephone directories like the Yellow Pages dominated all business-related searching, companies would call themselves 'A-1' in order to get listed at the top of the alphabetically ordered categories. The strategy revolved around the idea that the first company listed (e.g. 'A-1 Movers') would receive more calls than companies further down the list.