So turns out there's a specific sign in the UK highway code for "no cars carrying explosives allowed beyond here"
...
I mean
How often are cars going to be carrying explosives wtf
@Nine seeing that in my head I think "cars may explode in this area" not "cars with explosives aren't allowed in this area"
Cmon, British road sign designers, get it together!
@Anarkat
It's a red bordered triangle sign, if I recall, with a front facing car silhouette in black and a yellow explosion just behind it.