On a three-lane motorway, what does this sign mean?

Explanation: You must obey mandatory speed-limit signs above motorway lanes, including the hard shoulder. In this case, you can use the hard shoulder as a running lane but you should look for any vehicles that may have broken down and may be blocking the hard shoulder.

Category: Motorway rules

References: The Official DVSA Guide to Driving: Section 18, Highway Code: Rule 269