The regulations may provide that they shall only apply where the authorised person has reason to believe that the offence mentioned in paragraph 1(1) is being committed before such date as may be prescribed.

The regulations may provide that they shall only apply where the vehicle mentioned in paragraph 1(1) is in a prescribed area.

Different dates may be prescribed under paragraph 1(1) or sub-paragraph (1) above in relation to different areas prescribed under sub-paragraph (2) above.