There is no defence to an absolute offence. You could show that the offence is not made out ie the item was not in your possession or you had no knowledge of it. A couple of examples where no was prosecuted or the offence was not made out I saw in a previous job
Bloke found with drugs in his coat pocket whilst wearing it - said he didn't know it was there as he had left his coat hung up in the cloakroom and someone must have put the drugs in the pocket. Unable to disprove that someone did put the drugs there and nothing to show he did know the drugs were there
A machette found in the boot of a car. Driver said that he not long ago bought the car and had not checked the boot so it must have been left there by the previous owner. Unable to disprove the story and nothing to show he did know the drugs were there
Wacky baccy cigarette found on the floor of a car with 4 occupants. All denied knowledge of it. Unable to show who was in possession of the cigarette so no prosecution
Man being chased by police throws a packet over a hedge. After being caught they go back and find the packet which contains drugs. Suspect denies all knowledge. No fingerprints fond on the packet so not prosecuted.
Unable to show that the packet was the one thrown by the suspect.
That job taught me one thing - deny everything and let the prosecution prove it. I saw many, many times the prosecution only went ahead due to the suspects admission.