This case clarifies that a clean air zone charge applies from midnight to midnight. A vehicle remaining in a zone after 11.59pm becomes liable for the following day’s charge, even if the vehicle only remains in the zone for a limited period after midnight, and only due to heavy traffic. The circumstances described in this and such a case do not provide a ground of appeal under the statutory fixed penalty scheme. They amount to mitigation that the adjudicator does not have the power to consider.