Basically Rock 'n' Roll music that heavily emphasises on the singer's Cockney accent. Chas 'n' Dave are major contributors within this genre of music.
Rodney: Oit Derek! You heard that new Rockney record by those Chas 'n' Dave boys!? It's fucking mental I'm telin' ya that for nothin'!
Derek: Nice one son! I'll 'ave a butchers' into that!