Well kosher piece on the cockney dialect migrating to Essex and the evolving language of the East End in the Guardian. Though still not sure what nang means. Writer Nikesh Shukla makes some great points about how cockney has always been influenced by immigration:
Think about how much of cockney comes from different languages anyway, like Yiddish ("kosher"), German ("shtoom"), Romany ("wonga"). My mum always said that loads of cockney came from Hindi. "Pukka" is from the Hindi, meaning solid. "Blighty" is from the Hindi , meaning foreign land. "Bandana" is from the Hindi , to tie. "Cushti", again, from the Hindi , or happy. Bish-bash-bosh ... No one knows where that one comes from. Except Danny Dyer.
Click on the link to have a butchers at the whole piece.