—(1) Where a person uses a motor vehicle in circumstances such that under section 3 there is required to be in force in relation to his use of it such a policy of insurance or security as is mentioned in section 3(1), then, if any other person is carried in or upon the motor vehicle while the user is so using it, any antecedent agreement or understanding between them (whether intended to be legally binding or not) shall be of no effect so far as it purports or might be held —
to negative or restrict any such liability of the user in respect of persons carried in or upon the motor vehicle as is required by section 4 to be covered by a policy of insurance; or
to impose any conditions with respect to the enforcement of any such liability of the user.
(2) The fact that a person so carried as referred to in subsection (1) has willingly accepted as his the risk of negligence on the part of the user shall not be treated as negativing any such liability of the user.
(3) For the purposes of this section, references to a person being carried in or upon a motor vehicle include references to a person entering or getting on to, or alighting from, the motor vehicle, and the reference to an antecedent agreement is to one made at any time before the liability arose.