I just profiled the US release of the Vengeance Trails boxset. I'm convinced that the UK release is exactly the same product, except with a different J-cover (to give it a different, locality correct, EAN).

So, if anyone wants to profile the UK release, you can just copy everything from the US release (expect the UPC, of course) when my contribution has been approved. You're welcome! 

I bet that all Arrow releases that are released at the same time in the UK and the US are the same discs. All I have looked at are region AB. And for boxset children w/o UPC/EAN, I bet that the covers are identical, too. It just makes sense.

Edit: The UPC is on the bottom of the J-cover, so it's not on the cover scan, so you can even use the same cover scans for the boxset parent.