Quote ="Hillbilly_Red"check the small print: Warrington is outside Gtr Manchester and may not be covered by the £4. i used to be able to use a £4 from Rochdale to (such as) Hebden Bridge but suddenly there were two tickets: Gtr Manc and West Yorkshire... now more expensive.'"
I buy the ticket to use on journeys from Warrington on a regular basis with no problems.
The samll print states: Valid on day of issue on all First buses within Greater Manchester, including service 100 to Warrington.