Big thanks to John Moore for sharing this recent article on cockney slang used in the City of London as some old LIFFE traders I've talked to mentioned the slang but didn't know the origins or sometimes meanings. The link for the entire article is below and listed here are the numbers which I heard were used on the LIFFE floor.
Modern trading killing off "barrow boy" market slang
A SPANIARD - 1 - From the Spanish name Juan
A PRICKLY - 2 - A prickly pear
A CARPET - 3 - UK prisoners used to be allowed carpet in their cells after 3 years
LADY GODIVA - 5 - Rhymes with fiver
AYRTON - 10 - Tenner rhymes with Ayrton Senna, the late racing car driver
A BULLY - 50 - From the 50-point bullseye on a dartboard
A MONKEY - 500 - The 500-Indian rupee note used to have a picture of a monkey on it
*I'll also note/apologize for not posting much the past couple months. Besides moving, I've been busy trading, learning new software, switching clearing firms, constantly traveling, etc.... but now hope to get the blog going a little bit more although the distractions listed still remain.