Desperate -- What Movie Is This?!

Is it possible this was How Green Was My Valley? If not, what?!

It was between 1976 and 1978 on what I believe to be PBS, and I think it was Masterpiece Theater. Not sure. All Brits. A man is walking through low grassy foothills, obviously looking for something ... or maybe it's just very familiar to him but he doesn't know why. He sees what I perceived to be a very beaten up, very weathered bowler hat (or is it a porkpie?), the one with a lip all around it -- that had a bunch of holes in it and was weather-beaten, thread-bare. It sparks a memory in him. Cut to him remembering when he was a little boy, and he was in a ... cave? Shack? I want to say it was a cave. There were these British hillbillies? Deep back woods Appalachia folk? Toothless, Troglodyte, dirty types in overall type clothes -- and he's there with them, and they're doing a lot of laughing at things they find very amusing, but the boy is very uncomfortable and wants out now.

He has to pee. They tell him to go in a pot. it was white? Low wide chamber pot thingie? And it turns out that this is what he found in the low foothills as an adult, was an ancient chamber pot that was rusted with holes in it. Is this the same chamber pot he peed in, the adult man wonders? When he did, he was really scared and upset and yelled, "I want to wake up! I want to wake up!!" in a very thick English (Welsh?) accent. Cut to him in the foothills again, remembering this, wondering if it's evidence that it all really happened. My image at that point was that he was an older 50-ish or 60-ish man with the rusty pot.

I had originally thought parts of the movie, The Lathe of Heaven were also this mystery movie, but I since learned that they're separate. I don't know if my parents were flipping between two movies, or I was jusst putting two movies together. In any event, The Liverpool BritBillies is a real mystery. A couple people think it could be How Green Was My Valley, but I haven't been able to find a verbatim walkthrough of that movie to find the scene.

Can anyone help?!