I can't help as I left Oswaldtwistle 46 years ago, have lived in the Midlands, North East, the Middle East (world, not UK) and, for 32 years, Cheshire and, I'm told, I don't have a discernable accent.
I would, however, urge you to try Warrington (10 miles from where I live) in your quest into local accents further afield. The true Warrington tongue has a mixture of Manchester and mid-Lancs. It's a fairly horrible accent but, these days, it's being superceded by Scouse, as so many have moved this way from Liverpool, and it may well disappear in a couple of decades - which is a shame - even if it is horrible.
