Temporary speed limit signs

Q) Are the temporary speed limits above motorway gantries compulsory, or just suggested? No one ever seems to obey them
Maria Johnston, via e-mail

A) If the speed is surrounded by a red circle, then it is compulsory and must be obeyed. Go any faster and you risk a fine and points on your driving licence.

Advisory speeds are surrounded by flashing lights. These usually appear in bad weather or heavy traffic. While they arent compulsory, we strongly recommend that you stick to them.****