Yes, there are cable police in the UK insofar as all the cables and installation from the external mains supply to the wall sockets, the plugs that go in the wall and the fuses in the plugs that go in the wall. The plug/fuse that goes in the wall is specified to protect the power cable to the appliance from overheating. Interconnects and speaker cables are not covered as they don't get plugged into the wall AC.
There is a formal system of testing by certified test electricians, and they test and report on the entire installation, which is filed online and should be redone every 5 years. If your electrical installation is part of works controlled by the building police (called Building Control), you will not get a Building Certificate of compliance without the Electrical Certificate, Gas Certificate and Fire Certificate.
So if you make a fire insurance claim, you'd better have the certificates. If you're selling your property and don't have the certificates, the buyer will assume it is not compliant and the price will likely be reduced.
Most building works require permission from the local authority. All the documents are available online. When buying a property you pay a surveyor to check what has been done and that the work was certified when complete. They also check that work was not done without permission.
It's all about safety. For example, the inspectors told me that some glass doors separating the kitchen area had to be fire-rated to protect the upper floors of the house, which cost me an extra $4,000 over normal safety glass.