In Dickens' Pickwick Papers, there's a character "Sam Weller". Weller's dialogue is written somewhat phonetically, I presume, but I'm struggling to understand what accent Dickens is trying to portray. The main peculiarities of Weller's speech are using "v" where there should be a "w" and a "w" when there should be a "v". For example, he says "wery" instead of "very" and "avay" instead of "away". Weller is supposed to be from London, but this doesn't seem like any kind of London accent I've heard. Is this a particular archaic accent?
More importantly, what is Dickens telling us about Sam Weller by having him speak like this?