Southern England?

For The Winslow Boy I had to learn a second English accent. In addition to my generic RP English accent, I was taught (by our vocal coach, John, a Scot) a passable generic cockney accent.

And, in general, once I learned how the shape the words, I just had to pay attention to the usual things like saying them in the right order, putting the stresses in the right places, etc.

So Saturday night there I was, up on stage, minding my own business when I said:

"But I saw him in this room as big as life with my own eyes before y'all came back from church."

Yep. Violet the cockney parlormaid said "y'all."

I mentioned it to Anne, our AD, a little later and she told me that I should have said "youse."