Sir Winston Churchill once observed that Americans and the British are 'a common people divided by a common language' ...
Never was that as true as when describing the Cockneys.
You've certainly heard their accent, made famous in everything from movies based on Dickens and George Bernard Shaw novels to computer-generated gekkos telling real gekkos how to go forth and sell car insurance. The Australian accent has its roots in Cockney culture, as they comprised a large percentage of prisoners who were shipped there by the British when they viewed the Land Down Under as an ideal penal colony. Cockneys are the crafty characters from east London who admire those among their lot who can make a living simply by 'ducking and diving, mate,' which is their version of wheeling and dealing on a working-class level.
To be a 'true' Cockney, one must be born 'within the sounds of the Bow bells.' That's a reference to the St Mary-le-Bow Church in the Cheapside district of London 'proper.' Their sound carries to a distance of approximately three miles, which defines the Cockney digs better than any zoning ordinance could do.
The term 'Cockney' first appeared in the 1600s, but its actual origins are vague. Its first known reference was related to the Bow bells themselves in a period satire that gave no reason for the association.
Some believe that 'Cockney' came from the second wave of Vikings, known as the Normans. These were descendants of the Northmen ('Norman' was the French word for 'Viking') who settled in that part of northern France that came to be known as Normandy when King Charles the Simple ceded it to the Vikings in exchange for ceasing their annual summer sackings of Paris. William the Conqueror was a Norman, and when he took England in 1066, a considerable amount of French influence permeated the Anglican language.
Normans often referred to London as the Land of Sugar Cake, or 'Pais de Cocaigne,' which was an allusion to what they saw as 'the good life' that could be had by living there. Ultimately, this gave rise to a term for being spoiled, 'cockering,' and from there, Cockney was a short derivative away.
Cockneys are famous for dropping the 'H' from the start of words and infamous in the mind of every grammar teacher for their coining the word 'ain't' to replace the formal contraction for 'is not.' However, their most unique feature is their distinctive and catchy rhyming slang.
Legend has it that, during the course of their 'ducking and diving,' they would occasionally run afoul of the law. It was not uncommon for groups of Cockneys to be transported together to and from custody and courtroom, obviously in the company of policemen. So that they could speak openly to each other and deny the officers any ability to understand what they were saying, Cockneys devised a word/phrase association system that only the truly-indoctinated could follow. This became known as their rhyming slang.