Somewhere along the way I learned that uh-oo-aht-eh-pu-it has two totally different meaning in Mancunian and Cockney. Not sure what either of them mean but I could see trouble saying it to the wrong person in a pub.
Like Rod Stewart 
When I hear it, British people pronounce Worcester as what I would spell Wousta, “wou-” as in “would.” But I find it very hard to distinguish a barely rhotacized vowel from an unrhotacized one, though the British themselves clearly have no problem doing so.
Leominster is “Lemsta” in the UK; I have no idea how the one in Massachusetts is pronounced.
Lemstuh is similar to UK. Worcestor is MA is more like wuhstuh. There’s only the faintest R.
Being rhotic-speaking, I sometimes have that issue as well. I think the non-rhotic r is a lot like the dark l. Around here, the l in “calm” is not clearly articulated, but you can hear it. The vowel is palatized. Rhoticized vowels are also palatized, but more forward compared to dark-l vowels.
I remember testing the issue with a couple of non-rhotic friends: I had been very, very confused by the discussion of a new Pawn / Porn shop in town, but it turned out the two of them each had no problem distinguishing those words from each other.
I can work my way through the Boston accent pretty well but I was totally stymied at the landscape supply company checkout. I gave them the product number from tag on the pallet. There was some head scratching and back and forth among them and then someone asked me “Did you get code bricks?”. I had no idea what that meant, I repeated quizzically “Code bricks?” He said “Yes. Code.”. We stared at each other for a few moments and then someone else asked “Did they have holes in them? He’s trying to say Cored Bricks.”
I’ve had a few moments, too. Asking for directions once, I was told to turn onto “Easton Avenue”
“I can’t find it on the map,” I replied
“It’s a major street – Easton”
“Are you sure? Can you spell it?”
“Yeah – Easton – E - A -S -T -E - Ah – N – Easton.”
Another time I had stepped out of our laser lab (pronounced “Lasuh Lab”) while a long-running experiment was in progress. One of the junior scientists came running out, somewhat alarmed.
“Cal! The Lasuh! It’s Ocking!”
“It’s what?”
“Ocking! It’s Ocking!”
I had to run it over in my head a few times before it registered.
“It’s Arcing!” I shouted in triumph.
“Yeah, it’s Ocking! What do we do?”
I saw some Maryland license plates at a rest stop and decided to ask my fellow Marylanders what part of the state they’re were from. Took me a second to translate “Aston Shaw” (eastern shore).
As for English surnames: Featherstonehaugh is pronounced fanshaw, and Cholmondeley as chumley.
Just fail to get anyone going on about how to pronounce “Enroughty”.
One of the high schools I went to brought in a Bostonian to talk to us about underage drinking. Took me a moment to suss out that he was referring to parties rather than bathrooms.
Have any of you ever met someone from the UK or Ireland? These examples are the tame American versions of pronunciations that skip certain consonants. I’ve never had a problem understanding someone from Boston. But for Game of Thrones episodes, I need English subtitles.
I need English subtitles for everyone, so I don’t miss a word or phrase that’s not enunciated properly.
Isn’t St. John pronounced sinjin?
A woman on the next stool at the local pub asked a young server for “neck-a-roni”. After hearing it repeated, the server said “I’m afraid we don’t have that.”
After an hour of catching snatches of her conversation, it became apparent she was from somewhere Mediterranean, and I realized she’d been asking for a Negroni.
The conventional sign for a pawn shop should tell you.
Or maybe not.
Triorchidism!
Or the Medicis?
As a Mancunian I could probably tell you what it means but I can’t work out what it’s supposed to say.