half a bar

Definition

Slang

  • noun before decimalisation in 1971 half a bar was ten shillings; since then it has meant fifty pence. The phrase is London working class or cockney. ‘Bar’ is an archaic term, still occasionally heard in London, coming from a Romany word (bar or baur(o)) meaning a sovereign and, later, one pound.
http://www.dictionarycentral.com/definition/half-a-bar.html