Driving Examiner Guidance: Overtaking, meeting and crossing
The examiner should observe the candidate’s actions in overtaking and meeting other vehicles, and crossing the path of other traffic when they are turning to the right. Before overtaking, the mirror(s) should be used to observe following traffic, and appropriate signals given if necessary. While showing consideration for other traffic, the candidate should not give way unduly when it would be safe and proper to proceed. On the other hand they should not be inconsiderate, eg by turning right in the face of closely approaching traffic.
The above is taken from The Driving Examiners Manual.
Where appropriate it has been reformatted and edited so it only refers to the driving of ordinary cars (class b).