Yep ha even the normal ones

https://c8.alamy.com/comp/CYKB4F/30-mph-kill-your-speed-not-a-child-road-sign-uk-CYKB4F.jpg

Road signs, like safety regulations, are written in blood. There was a big drive a few years ago to get the aristocracy to donate blood so that they could use the colour blue on road signs.