GSS: Allan Smethurst's accent was definitely Norfolk: I doubt if he'd retain much of the Lancashire accent if he moved away from there when he was 2! Kids can change their accents quite successfully maybe up to mid-teens, and tend to talk more like their peers than their parents or folk in place they were born.
I was born in Glasgow but no way have I a Glasgow accent: I speak with a slight Suffolk accent, the place where I grew up.
My daughter went through three different accents according to where we lived, before coming to Scotland when she was 9: she, and our son, who came here aged 3, both have an unequivocal Edinburgh accent.