The language of the Absolute Beginner

See my recent criticism of the way the teenage narrator talks in Colin MacInnes's Absolute Beginners. I now find MacInnes offered an explanation in his 1961 essay collection, England, Half English. He says that in the novel and his earlier City of Spades he attempted

'poetic evocations of a human situation, with undertones of social criticism of it: wildly romantic in mood, and as rigorously analytical as I can be.... To convey this [what? PM] to the reader I chose a language for "coloured people", or for teenagers, that was almost entirely an invented one... Strict naturalism of language... would, in the case of social exotics such as these, result in a 'period dialect': pedestrian, and fixed for ever in the time-stream.'

So, he claims, Dickens invented a dialect for Sam Weller. Well, good try, but for me it doesn't work.