From what I have read on here there is some further complication in the way individuals in one area talk. For example in Liverpool different people in the same family will pronounce sounds differently. For example, look, book and cook can be Loooch, Cooock and Boooch (the ch being like you are about to spit is the best way I can describe it), it can also be Luch, cuch and buch. That is just in my family. I hope that makes sense. Ha ha. You will hear both in Liverpool.
The Glottle Stop is a great leveler which people don't seem to bring up very often when it comes to pronunciation. It happens all over the country. My local station is West Allerton but pronounced West Aller'n by I would say a great many people, not my dad, ha ha. Things like glottle stops can cause a lot of issues with foreign visitors. Ha ha.