Spent a week in a hostel in London many years back. Landlady was strictly Cockney and I couldn't understand a word she said all week long!
in a hostel in dover my wife and i visited with a very old man who was cockney. he spent thirty minutes trying to, as far as i could make out, tell us about his time as a japanese pow. whatever the case, after about ten minutes, i gave up asking him to repeat everything and spent twenty minutes politely nodding and smiling.