Scotland Bill

I have one small question. I take the point about local authorities imposing speed limits as they wish, but motorways of course come under the Highways Agency. If I am I right, and if there is therefore a variation in a motorway speed limit, as there can be—there is, for instance, on the very good new M74 through Glasgow, where a 60 limit goes down to a 50 mile an hour limit—who imposes that? Who is consulted, and who is putting that speed limit on?