It was more a conversation along the lines of what if it fell off.
He said getting a new VIN plate made is troublesome, and if the tester believes the plate has been removed or tampered with it will fail. I realise the sense, but I thought he was being a touch anal about the rivets should match.
That said he also failed the car first attempt because the sidelights weren't white enough!
Edit- just noticed it says permanently secured. A nut and bolt won't do.
Two part epoxy resin I reckon then.