This appears to be the weakest link in a weak chain, with little by way of examination at the ports of containers and correspondence.
I understand that the Ports are a vital trade resource and checking containers interferes with their smooth, punctual and precise running. But it appears little attention is paid to the ports and unlike the channel tunnel, ANPR will not reveal movement as cars and components are sealed in a steel box.
There also appears to be a ‘them-and-us’ relationship between the UK’s ‘conventional’ police constabularies and those at the Ports who are, I understand (at least some), private contractors.
I am aware of instances of the Ports police / authorities demanding a ‘ransom’ for seizure and return of a vehicle, a bounty equivalent to 5% or 10% of the vehicle value. A failure to pay this sum up front will see the vehicle allowed to be shipped to its intended destination. This conduct appears to fly in the face of the principles of policing.
Whilst this instance might have been unusual, and dates from a few years ago, with the Brexit chaos about to descend upon us, you may well think that detecting stolen motor vehicles will be the least priority agenda item of any Port administration authority.