Originally Posted by 
JDNSW
				
			 
			I was advised by a local blue slip inspector that the safety chain on my trailer was not legal because it was bolted to the trailer - safety issue because bolts can come undone. He implied it should be welded, but I would think a properly locked bolt should be OK. (Mine was held in a similar manner to your proposal with a 12mm socket head screw tapped into the 10mm plate under the coupling and through it into the top of the towbar, so not feasible to visibly lock. (Never shown any signs of coming loose in the 20+ years I have owned it.