There already exist's a system for mot and taxation of articulated lorry trailers and the draw bar (wagon & drag) trailers within the LGV taxation class.
As each modern caravan already has a unique VIN number stamped on the chassis plate, there is captivation available there.
I also expect that some where there is an EU directive that the government will follow blindly like sheep, issue registration numbers for trailers. However this might be more of a cost than a saving. For instance in my case< I have three trailers. Our caravan, a goods trailer and a boat trailer. The later two I have built from scratch myself and they do not have any unique VIN number at all. The boat trailer does not have lights fitted and carries a lighting board instead. The same lighting board is used on the goods trailer. So if we were to have registration numbers for trailers I can see there being several infringements of the current regs where the number plate of the towing vehicle curently not only has to be displayed, but capable of being illuminated at night.
As for MOT's on trailers (inc'l caravans), the sooner that comes into play the better. If I can build two trailers without them being certified as road worthy then probably 50% of the trailer users can. That's a frightening thought!! There has been a few debates on MOT's for caravans herebut the actual pheasability of using existing MOT stations probably is the bigest obstical.
However in the current economic climate, I can see the MP's grasping any chance to divert attention from their own inefficiencies. Just last night on the news it was revieled that the MP's use paper at £80 a box rather than use the cheapest paper for internal bull**1t, costing only £4 a box. It was muted that they could save millions by just buying as a unified group and going to the cheapest supplier. It was said by one offical that doing that would cost jobs. Probably in the "old boys club" I would agree, as they have been sell tat at inflated prices for years as an "approoved supplier", however opening up the purchasing to enable true price competition would generate healthy competition with the fitest being the survivors.
I've worked in the motor industry where you were given a product price by the customer and it was up to you to be come efficient enough to be profitable. I found it a satisfying job being a process technician and deriving production methods in such a tightly run business. We managed to be profitable with room to spare.
Atb steve L.