Different kinds of freedom. In London you can legally jaywalk naked while drinking a beer in front of a cop and know that even if you really pissed the cop off, you'd never get shot for it.
It's oddly specific mockery, like Ozzy is England's international representative. I don't know, maybe he is. But I doubt Birmingham even inspired the meme, this is probably a caricature of Dick Van Dyke more than anyone.
To be fair, Brits seem to think New Yorkers go "oi" and they don't really either.