No, they do not need a warrant.
For live time urgent urgent enquiries, where life or limb may be at risk, it need only be authorised by a supernintendo.
For slow time crime enquiries there is an exemption in DPA which allows the data to be gathered for the purposes of "the prevention or detection of crime". However, as an arriss covering exercise the unofficial convention is that an officer of the next rank up will give their approval and that will be recorded before the application for the location data is submitted. If the company refuse, and assuming the enquiry justifies such drastic action, the dibble can just pitch up and seize the equipment wholesale under S19 of PACE, so they almost always cooperate in full once the boxes have been ticked.
In my case i only have a dumb phone, and almost never carry it anyway as my car has a built in phone that I can switch on and use in an emergency. It'll be eyes-on the hard way if anyone tracks me, and that takes 4 people minimum to do effectively, so that dog's not ever going to bark.
She phoned me on Tuesday, but again i wasn't dressed incorrectly, so i didn't answer it.š§
