Background of Cockney English:Due to the fact that London is both the political capital and the largest city within England, Wells, (1982b) doesn’t find it surprising that it’s also the country’s "linguistic center of gravity." Cockney represents the basilectal end of the London accent and can be considered the broadest form of London local accent.(Wells 1982b) It traditionally refers only to specific regions and speakers within the city. While many Londoners may speak what is referred to as "popular London" (Wells 1982b) they do not necessarily speak Cockney. The popular Londoner accent can be distinguished from Cockney in a number of ways, and can also be found outside of the capital, unlike the true Cockney accent.
The term Cockney refers to both the accent as well as to those people who speak it? The etymology of Cockney has long been discussed and disputed. One explanation is that "Cockney" literally means cock's egg, a misshapen egg such as sometimes laid by young hens. It was originally used when referring to a weak townsman, opposed to the tougher countryman and by the 17th century the term, through banter, came to mean a Londoner (Liberman, 1996). Today's natives of London, especially in its East End use the term with respect and pride - `Cockney Pride'.)
Cockney is characterized by its own special vocabulary and usage, and traditionally by its own development of "rhyming slang." Rhyming slang, is still part of the true Cockney culture even if it is sometimes used for effect. More information on the way it works can be found under the Cockney English features section.
Geography of Cockney English:London, the capital of England, is situated on the River Thames, approximately 50 miles north of the English Channel, in the south east section of the country. It is generally agreed, that to be a true Cockney, a person has to be born within hearing distance of the bells of St. Mary le Bow, Cheapside, in the City of London. This traditional working-class accent of the region is also associated with other suburbs in the eastern section of the city such as the East End, Stepney, Hackney, Shoreditch Poplar and Bow.
Sociolinguistic issues of Cockney English:The Cockney accent is generally considered one of the broadest of the British accents and is heavily stimatized. It is considered to epitomize the working class accents of Londoners and in its more diluted form, of other areas. The area and its colorful characters and accents have often become the foundation for British "soap operas" and other television specials. Currently, the BBC is showing one of the most popular soaps set in this region, "East Enders" and the characters’ accents and lives within this television program provide wonderful opportunities for observers of language and culture.
Features of Cockney English:Some of the more characteristic features of the Cockney accent include the following:
This affects the lexical set mouth vowel.
Wells (1982b) believes that it is widely agreed that the "mouth" vowel is a "touchstone for distinguishing between "true Cockney" and popular London" and other more standard accents. Cockney usage would include monophthongization of the word mouth
Example:
mouth = mauf 
rather than mouth 
Wells (1982b) describes the glottal stop as also particularly characteristic of Cockney and can be manifested in different ways such as "t" glottalling in final position. A 1970’s study of schoolchildren living in the East End found /p,t,k/ "almost invariably glottalized" in final position.
Examples:
cat = 
up = 
sock = 
It can also manifest itself as a bare 
as the realization of word internal intervocalic /t/
Examples:
Waterloo = Wa’erloo 
City = Ci’y 
A drink of water = A drin' a wa'er 
A little bit of bread with a bit of butter on it = A li'le bi' of breab wiv a bi' of bu'er on i'. 
As would be expected, an "Estuary English" speaker uses fewer glottal stops for t or d than a "London" speaker, but more than an RP speaker. However, there are some words where the omission of ‘t’ has become very accepted.
Examples:
Gatwick = Ga’wick
Scotland = Sco'land
statement = Sta'emen
network = Ne’work
In the working-class ("common") accents throughout England, ‘h’ dropping at the beginning of certain words is heard often, but it’s certainly heard more in Cockney, and in accents closer to Cockney on the continuum between that and RP. The usage is strongly stigmatized by teachers and many other standard speakers.
Examples:
house = ‘ouse
hammer = ‘ammer
Another very well known characteristic of Cockney is th fronting which involves the replacement of the dental fricatives, 
and 
by labiodentals [f] and [v] respectively.
Examples:
thin = fin 
brother = bruvver 
three = free 
bath = barf 
Examples:
dinner = dinna 
marrow= marra 
The voice quality of Cockney has been described as typically involving "chest tone" rather than "head tone" and being equated with "rough and harsh" sounds versus the velvety smoothness of the Kensington or Mayfair accents spoken by those in other more upscale areas of London.
Cockney English is also characterized by its own special vocabulary and usage in the form of "cockney rhyming slang". The way it works is that you take a pair of associated words where the second word rhymes with the word you intend to say, then use the first word of the associated pair to indicate the word you originally intended to say. Some rhymes have been in use for years and are very well recognized, if not used, among speakers of other accents.
Examples:
"apples and pears" – stairs
"plates of meat" – feet
There are others, however, that become established with the changing culture.
Example:
"John Cleese" – cheese
"John Major" - pager
Numerous examples and usage of rhyming slang can be found online. See Note 2 for information.