Babe.

In Polari, ‘Chavvy’ means child. It comes from Romani (a lot of Polari did - one of its influence was a language used among travelling performers). You can see it in the Polari bible - Exodus begins:

Now these are the names of the chavvies of Israel, which trolled into Egypt; every homie and her household trolled with Jacob.

The word current use of ‘chav’ and the Polari use of ‘chavvy’ almost certainly have the same origin of the Romani word for child and various slang uses of that term in English.