Lancashire dialect is Middle English. Lots of thees thous and thines and and third person vowels. And words no longer used in modern English.
My father used to tell of being in the RAF during world war 2 and being stationed in North Wales. They would go into a pub where the locals were speaking English but as soon as they arrived, the locals all switched to Welsh. One day he went in with a fellow Lancastrian and they spoke in Lancashire dialect - at which point the locals switched back to English as they didn't realise my father and his friend were English from their speech.
My grandparents all spoke Lancashire dialect, my father did, my mother did a bit, but I know very little