inconsistent accents?

It plays like it was shot chronologically, and they were all (Stamp, Redgrave, Arterton) trying cockney accents, and then at some point, they realised it wasn't working, and gradually defaulted to their own middle class register.

It would have been better if they'd shot the whole film like that, Stamp's performance in particular, seems ill at ease with trying to sound 'more common.'