Highway Code Rule 264

You should always drive in the left-hand lane when the road ahead is clear. If you are overtaking a number of slower-moving vehicles, you should return to the left-hand lane as soon as you are safely past. Slow-moving or speed-restricted vehicles should always remain in the left-hand lane of the carriageway unless overtaking. You MUST NOT drive on the hard shoulder except in an emergency or if directed to do so by the police, traffic officers in uniform or by signs.

Laws

• The Motorways Traffic (England and Wales) Regulations 1982: Regulations 5, 9 & 16(1)(a)
• The Motorways Traffic (Scotland) Regulations 1995: Regulations 4, 8 & 14(1)(a)
• Road Traffic Act 1988: Sections 35 & 186 as amended by Traffic Management Act Section 6