I was raised by an English mum[0] (scouse, to be precise -actually, her mum was scouse, me mum was posh).

I've traveled all over the world, and the one place that I've had the most difficulty understanding, was London. Cockney is hard. It's not just the patois. It's the cultural references and slang.

[0] https://cmarshall.com/miscellaneous/SheilaMarshall.htm

Not many Cockneys in London these days, they're all in Essex