Linked video on the Hull accent - one clown tells us that Hull people say "er ner" for "oh no", "sner" for snow, and "fern" for phone. He then reads a poem containing the words toad and folk. Does he pronounce them TURD and FURK? Of course not, he says tawd and fawk. I think it's called cognitive dissonance; or maybe it's brainwashing.
Anyone who wants to hear the Hull accent in all its glory should listen to the actor Peter Martin. I don't know, maybe he's retired, he used to be in Emmerdale. Barry Rutter, another Hull-born actor, does it when playing rough-arses, but, being a stage actor, he probably has other accents. Tom Courtenay, however, has gone all posh on us, though I seem to recall him doing "Hull" in "King and Country", when he played a squaddie sentenced to death for desertion.