The procedure is the same whoever is driving. The registered keeper of the vehicle will be sent a Notice of Intended Prosecution (NIP), detailing the offence. Plus, a document called a Section 172 notice. Whether you agree with the NIP or not, within 28 days you must complete the Section 172 notice declaring who was driving the car at the time of the offence.
The driver will then receive either an option to attend a speed awareness course if they have not been convicted of any other speeding offences in the past three years and have been caught driving over 10% plus 2mph of the limit, but below 10% plus 9mph. In a 30mph zone, this means anything between 35mph and 42mph, while in a 70mph zone it means anything between 79mph and 86mph. (These figures are only guidelines and different police forces may set different limits.)
In most other circumstances, they are likely to receive a and a minimum of three penalty points.
What happens to an ADI whose pupil breaks the speed limit?
Usually nothing! Learners accept that they exceeded the speed limit, accept the punishment and the matter ends there.
But not always! Every so often a learner, their mum, dad, boyfriend or other interested party kicks up a fuss. This does nothing to help the learner, they have still committed the offence and will still be punished. However, the instructor is now in a somewhat invidious position. A professional driver trainer clearly has a duty of care to their client defined as a legal obligation to safeguard others from harm while they are in your care, using your services, or exposed to your activities. To ameliorate the situation some ADIs offer to pay the pupils fine or the cost of a speed awareness course.
In some cases, police attention is brought to instances of learners speeding or committing other moving traffic offences. I have never heard of an ADI being charged with the aiding and abetting a learner to break the law after all instructors don’t have dual accelerators. However, there is also the offence of causing or permitting an offence to take place.
For these offences, the endorsement codes are like those for the original offence, but with the number 0 on the code changed to 4.
For example, if an instructor permits a client to exceed the speed limit he might end up with an SP34 endorsement on their licence, a fine and 3 to 6 penalty points. In a worst-case example, say client traveling at 60 mph in a 30 mph speed limit the instructor could be disqualified from driving.