Speed camera and laser guns detectors, illegal in the south but legal in the north. Some people also have jammers in their cars which are illegal.
If photographed by a speed camera, if you 'cannot remember' who was driving ask for a copy of the photo. In 95 % of cases they drop the prosecution, its their legal duty to identify the driver commiting the offense.
If done by a speed gun, ask for a copy of the calibration cert, speed guns must be tested at regular intervals and issued with a calibration cert, its your legal right to see the cert. In many cases the calibration certs are out of date.
The prosecution is illegal.
If court doing 100 mph + get a barriester to represent you in court, it will save you your licence.