These are people brought in from outside the University to offer an objective view of the students’ work at assessment. There are External Examiners appointed to each programme. One or more of them is normally involved in viewing work, talking to students and gaining an overview of how the assessment has been conducted. They add their views in discussion with staff to balance the staff’s internal assessment.
This arrangement serves to safeguard against any undue bias or too narrow an outlook affecting the internal assessment. The External Examiners report orally and in writing to the Board of Examiners, which take serious account of their opinions.
You can read more about the role of the External Examiner, and additionally access a list of all current External Examiners and the institution they work for, for every Programme and module, here.