Green’s Dictionary of Slang

broad n.1

1. [17C–19C] a sovereign, a 20-shilling coin.

2. [1920s+] usu. in pl., money.

3. [1970s] any form of documentation, e.g. identification papers, rations book, driving licence.

4. [1970s+] a credit or similar card.

5. see broads n. (1) and combs. for all refs. to playing cards.