asked the Secretary of State for Transport if he will take steps to encourage motorway users to adhere to rule 165 of the Highway Code about not travelling continuously in the fast overtaking lanes.

Yes. The Department takes every opportunity to remind motorists that they should use the outer lanes of motorways for overtaking only. Since June 1985 some 32 million leaflets on lane discipline have been issued with vehicle excise duty reminders. Experimental "Keep Left" signs have been installed on the M1. Their impact is being monitored.