Is this speed sign enforceable

[mickmcpaddy]

I've seen this in a few places now down the M6 and M5. Sometimes its used as a repeater in the variable speed limit section but sometimes it is illuminated before any limit change via the ganteries. Namely on the M5 around Glouster in the new "smart motorway".





Obviously some limit signs are advisory like the 50 with the flashing beacons or the square signs saying "max 50" etc round bends and such like, but the one above concerns me, one its the official symbol of a limit sign and 2 there are Hadecs 3 cameras bolted to the side. However I'm going for no, they're not enforceable for no other reason than the numbers are yellow and not white. But its nice to be sure.