Even the new ones that require certs don't have to be welded by anyone certified or competent, just needs to look 'okay' to the guy IVA testing it over a terrible MS Team video call....
The (proposal of) banning welding on cars is a complete crock if you think about it.
Take my scabby old Sorento. It has rot in the bottom of one of the wings, just a couple of inches from the bottom. It will pass an MOT because it's non structural being a body on chassis construction. If I weld it up it would fail? That makes little sense to me.
There's a possibility that they could in the future insist on panel replacement rather than patches, cant see how this could be policed if everything is gagged in stone guard.
correct me if I'm wrong but I don't think there's even any legal requirements for opening a business, lets call it 'The Trailer Welding Company', anyone could do it, would be daft but you don't even need insurance if you're a sole trader
can't see 3.5t trailers having MOT's, and if they do it will surely have to be 'trailers manufactured from xx date'