Technically, yes, because car insurance follows the vehicle, not the driver. So if you don’t have an insurance policy of your own, and you borrow your friend’s car, you can drive it with the protection of their insurance policy. However, car owners should keep in mind that if an accident occurs while their car is being loaned to another driver, it will affect the car owner’s premium (not the premium of a car-borrower). So be sure you trust anyone that you lend your vehicle to, especially if you want to have low cost car insurance in London.