Which animal's name is a London slang term for £500?

London slang is a mixture of words and phrases from around the globe. It reflects the diverse ethnic and cultural makeup of the city's population. Because London occupies such a dominant economic position in the United Kingdom, slang originally unique to the city has spread across the UK. Conversely, slang from outside London has migrated in along with people seeking work in the capital. Cockney rhyming slang and Multicultural London English is probably the best known form of London slang.

London slang about money is believed to have been imported from India by returning servicemen during the nineteenth century. The terms monkey, meaning £500, and pony, meaning £25, are believed by some to have come from old Indian rupee banknotes, which it is asserted used to feature images of those animals.

Cockney slang for one pound - Huckleberry (Hound - pound), saucepan (lid - quid), and squid is also slang for quid.