I think this national vs local police force thing needs a bit of explaining.
Years ago you could be speeding in one county, cross the county line (e.g. from Devon to Cornwall) and they wouldn't be able to catch you. The cop would have to back off at the 'border'. Or you could get a first offence caution, e.g. for drugs or shop-lifting in one county, then do the same offence in a different county and get another caution rather than be prosecuted properly.
Those days were over a long time ago, when computers arrived those gaps in the system went.
More recently the local stations have been closed with these local districts getting merged. The nearest cells might be in the big town twenty miles away rather than the local police station down the road. That might only have admin staff.
Then the police are now expected to follow everything up themselves using some tablet computer things they have been given. In the olden days someone back at the station would do all the follow up work contacting the victims of crime etc. Nowadays the constable who happens to be on the scene has to follow the incident up through to the end with a tablet computer instead of a team effort.
The government have chosen to make many cuts to the police force which is a little bit silly. The police are important for staying in power and any government needs them on their side. Cutting their pensions, making them work a not so local 'local' area with 'them and us' merger problems and undermining their effectiveness is just plain silly. If there was some type of Brexit related rebellion in the country then the police are no longer 'bought' enough to be guaranteed to always be on the side of government. It has got to that stage of pissing them off.
Anyway, the police are sadly quite underfunded and, as a consequence, there is nothing to fear from this new 'let's read your phone' ruling. The police have enough problems of their own.