Sorry for bumping an old thread but I think it's important to produce some facts on an important subject of road safety.
I've recently just had a driving instructors video of over 1 million views removed from Facebook by complaining to the DVSA about incorrect teaching of overtaking on the left.
It's permitted in congestion and slow moving queues. A few cars hogging the middle lane is neither.
The offence is committed when overtaking on the left when not permitted to do so.
Let's look at the Highway Code.
"Overtake only when it is safe and legal to do so. You should
only overtake on the left if the vehicle in front is signalling to turn right, and there is room to do so
stay in your lane if traffic is moving slowly in queues. If the queue on your right is moving more slowly than you are, you may pass on the left."
www.gov.uk/guidance/the-highway-code/using-the-road-159-to-203
"Overtake only on the right."
"Do not overtake on the left or move to a lane on your left to overtake. In congested conditions, where adjacent lanes of traffic are moving at similar speeds, traffic in left-hand lanes may sometimes be moving faster than traffic to the right. In these conditions you may keep up with the traffic in your lane even if this means passing traffic in the lane to your right. Do not weave in and out of lanes to overtake."
Paying close attention to -
"Do not overtake on the left or move to a lane on your left to overtake."
www.gov.uk/guidance/the-highway-code/motorways-253-to-273
"Although failure to comply with the other rules of the Code will not, in itself, cause a person to be prosecuted, The Highway Code may be used in evidence in any court proceedings under the Traffic Acts (see The road user and the law) to establish liability. This includes rules which use advisory wording such as ‘should/should not’ or ‘do/do not’."
www.gov.uk/guidance/the-highway-code/introduction
Which moves us on to the traffic act in question.
"The offence of driving without due care and attention (careless driving) under section 3 of the Road Traffic Act 1988 is committed when the defendant's driving falls below the standard expected of a competent and careful driver - section 3ZA(2) of the RTA 1988.
Some examples of careless or inconsiderate driving are:
overtaking on the inside;"
www.cps.gov.uk/crime-info/driving-offences
The actual legislation states
"A person is to be regarded as driving without due care and attention if (and only if) the way he drives falls below what would be expected of a competent and careful driver."
www.legislation.gov.uk/ukpga/1988/52/section/3ZA
Which means if not following the highway code and overtaking on the left when not permitted, you'd be committing an offence as a competent and careful driver would be following the highway code and overtaking correctly.
To back this up, we'll look at a solicitors website
"Adherence to the rules/guidance of the Highway code will typically mean a driver would not be found guilty of careless driving. However, the inverse is also usually correct, in that, an individual that drives in a manner not consistent with the Highway code would typically be found to have acted in contravention of Section 3 of the Road Traffic Act 1988, careless driving."
freemanssolicitors.net/for-you/driving-offences/careless-and-dangerous-driving/#if-i-drive-within-the-rulesguidance-set-out-in-the-highway-code-can-i-be-guilty-of-careless-driving
If you want more, the Police posted about this very topic.
"OFFENCE
Overtaking on the left is lawful if done in accordance with the above guidance. However, whilst there is no specific offence of overtaking on the left, if a driver undertook another vehicle, other than in the circumstances described above e.g. in the case of someone hogging lane 2 on a motorway, they may be prosecuted for careless driving."
www.westyorkshire.police.uk/ask-the-police/question/Q891