1) The UK 'Construction and Use Regulations' are adopted from elsewhere. I could give you a guess as to who recommends that we adopt them, and you'd be surprised that it isn't, in this case, the EU.
In fact, it is the UN's Economic Commission for Europe (UNECE), a body, based in Geneva, which exists to remove trade barriers between European countries. They are goodies, on the whole (if you've ever used a 'green card' for insurance purposes abroad instead of having to deal with foreign insurers, the UNECE are the ones to have thanked).
This is why I'm rather baffled as to why this business owner is calling for a test case under UK law. A better approach, and one which would likely be less costly if he could get their ear, would be to petition the UNECE to add another class of vehicle to the current recommendations. Considering that the design of this vehicle is supposed to be quite revolutionary (regarding the arrangement of axles, a determinant of maximum vehicle lengths in UNECE recommendations), this would have been a more logical first step.
But then that might not have attracted the BBC to send a camera crew as readily as an arranged confrontation with police, would it?
Which leads to 2) Why the police? There is a body paid for by our taxes to deal with transgressions and disputes surrounding heavy goods and passenger road transport.
VOSA can also bring prosecutions, they have roadside inspectors and everything. If VOSA pull you over on a motorway and deem your vehicle to have broken a C&U reg, it can issue one of six different types of prohibition notice.
We pay for the bloody sods, why not use them in this instance? Or, again, are the police more photogenic for the BBC cameras?
Sniff the publicity angle yet?
It's OK. I'm finished, you can wake up now.