163 says:
##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
https://www.gov.uk/using-the-road-159-to-203/overtaking-162-to-169
268 says:
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.
https://www.gov.uk/motorways-253-to-273/overtaking-267-to-269
Therefore you do NOT pass on the left at all unless:
moving past a vehicle turning right or
you are in slow moving congested traffic (ie a 'traffic jam') and the traffic in your lane is moving more quickly than a that in a lane to your right, in which case you are authorised to keep up with the traffic in your lane.
Any other interpretation is wrong.