Going back to AF and his Hammersmith & Fulham PCN for his motorbike being driven by an unidentified garage worker on the wrong side of a 'keep left' sign, H&F parking dept has told me the PCN was issued under the London Local Authorities and Transport for London Act 2003. The Act states:

"SCHEDULE 1. Representations against penalty charge notice: (4) The grounds referred to in sub-paragraph (1) above are: (c) that at the time the alleged contravention or failure took place the person who was in control of the vehicle was in control of the vehicle without the consent of the owner; Section 24: Defence of due diligence (1) In proceedings for an offence under this Act it shall be a defence for the person charged to prove that he took all reasonable precautions and exercised all due diligence to avoid the commission of the offence. (2) If in any case the defence provided under subsection (1) above involves the allegation that the commission of the offence was due to the act or default of another person, the person charged shall not, without leave of the court, be entitled to rely on that defence unless, no later than 7 clear days before the hearing, he has served on the prosecutor a notice in writing giving such information as was then in his possession identifying or assisting in the identification of that other person."

AF obviously did not consent to what the garage worker did. But he did pass on to H&F such information as was then in his possession identifying or assisting in the identification of that other person. Both defences mean the PCN should have been withdrawn.