The earliest recorded instance of (cockney) rhyming slang was around 1838, just as the police force was being established, and that is believed to be significant. I did find a book on Google Books which gave details, but I didn't save the link.

Yes, there are many expressions still in common use - have a butchers (Hook=look), half-inch (pinch) , rabbit, get down to brass tacks (facts), and many people don't even know they are using it.

A load of cobblers = cobblers awls
Not a dicky bird = word
Dicky bow = a bow worn with your dicky dirt - shirt