Applying the rules of the road

Take a look at this clip

So the first question is one of knowledge.  As a PDI you will need to know whether something is either legal or not (ref to 129 of HWC).

Then it becomes a question of suitability.  In these circumstances is it wise to be overtaking the cyclist at this point?

And once you have those answers clear in your mind, then you need to decide how you go about testing for understanding with your pupil.  There could be many reasons why a pupil does the action they do.  Depending on the level of verbal instruction that you have both agreed upon has a bearing on what is mentioned prior to this happening and yet, safety has to be maintained.

So this becomes a balancing act around the issue of allowing your pupils the freedom to demonstrate independent driving, versus a driving instructors desire to apply the law and control all driving actions appropriately for safety, and finally the opportunity for a pupil to learn from mistakes.  

It is important that pupils are given the freedom to make mistakes (not ignoring the combined responsibility on both parties to maintain safety), because fundamentally it is better to make mistakes now with you supervising.  When a driving instructor over-instructs, any little chinks such as this example do not occur as the instructor immediately flys into "helicopter instructor" mode and controls the situation.  By restraining pupils in this manner, it is robbing opportunities for deeper levels of learning.