Quote: karetaker "Those areas south of the river Latchford etc were moved into Lancashire in 1889 due to the majority of the town already being in Lancashire'"
The boundary change was because of the construction of the Manchester Ship Canal which was has a much straighter course for a boundary than the River Mersey which meanders a lot..
The area of Warrington North of the Canal which had previously been in Cheshire was deemed to be in Lancashire.
The part of Warrington South of the Manchester Canal wasn`t allocated to Lancashire and hence that part of Warrington was still Cheshire.