Meaning of A1 in English

A1

I. A1 /ˌeɪ ˈwʌn/ BrE AmE

the A1 a main British road that goes from London to Edinburgh

II. A1, the /ˌeɪ ˈwʌn/ BrE AmE

a main British road that goes from London to Edinburgh

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.