How would it be illegal for a provisional licence holder to drive?

Explanation: When driving a motor car, a learner driver who holds a provisional driving licence must
- display red L plates (or D plates in Wales) to the front and rear of the vehicle
- be insured to drive the vehicle
- be accompanied by someone who's at least 21 years old and who has held for at least three years (and still holds) a full licence for the category of vehicle being driven.

Category: Band 3 driving test

References: The Official DVSA Guide to Driving: Section 2, Highway Code: Page 122