Where an accident occurs within Greater London resulting in the death of a person, and it is alleged that, the accident was due to—
(a) the nature or character of a road or road surface, or
(b) a defect in the design or construction of a vehicle or in the materials used in the construction of a road or vehicle,
the coroner holding inquiry into the cause of death shall send to the Secretary of State, or to such officer of his as the Secretary of State may direct, notice in writing of the time and place of holding the inquest, and of the adjourned inquest; and an officer appointed by the Secretary of State for the purpose shall be at liberty at any such inquest to examine any witness, subject nevertheless to the power of the coroner to disallow any question which in his opinion is not relevant or is otherwise not a proper question.
In this section " road " has the same meaning as in section 27 of this Act.