I occasionally get advertising emails and have had one from PoliceComplaints.co.uk
The linked website says "PoliceComplaint.co.uk do not give legal advice; Our service is limited to the process and administration of Actions Against The Police Claims."
So it's a claims handling firm taking a cut from referring claims on to its panel, which currently only includes Satchell Moran Solicitors in Liverpool. That firm does say on its website that it deals with police complaints, amongst other areas.
I do find this email very interesting, though. Claims handlers and lawyers often have a very good grasp on the zeitgeist, as well as a sharp eye for possible sources of income.