Bicester (Bister) and Gloucester (Gloster) are another couple of gotchas off the top of my head, and it's not like it even stops with places with *cester in the name.
The accent here means that the phrase "pork pie" becomes "poo-wuk paaah" (stress on "poo" and "paaah") and the related steak-and-kidney-pie (which is served upside-down) was called a "babby's edd" (although I'm not sure if that's actually from nearby Bolton and is less about pronunciation I guess).