I've always understood that motorway X signs surrounded by a red ring are mandatory - but what if there's no red ring?

I've always understood that motorway X signs surrounded by a red ring are mandatory, so if you don't obey them, you deserve what you get. However, I have also seen these signs without the red ring around...

I have serious safety concerns about Smart motorways - what's your opinion?

I commute along part of the M60, which for the last three years has been in the process of being "upgraded" to a Smart motorway. It has been without a hard shoulder while the work is carried out and almost...