Further north than Watford Gap services, if you ask me (person from Coventry, here. Remember Coventry: used to be a prosperous place, gutted by 5 decades of neglect by all parties?). They make an exception for the pretty bits of Northants -- so</> pretty, darling, and room for the children's ponies -- but kick Northampton in the teeth. And everywhere else is completely off their radar.
Home rule for Mercia, says I.