I shall write to the hon. Gentleman with further information. I am happy to underline the principal point that, in the national interest, the Bill allows us to deny access to sensitive areas. I am not able at this time to say precisely in what circumstances the Secretary of State and other senior members of the Government would seek to exercise that discretion. Clearly, it would be exercised in a matter of great national importance. As I have said, I cannot go into details at this time.