French higher education system is quite singular: besides traditional universities (following Bologna Process scheme with Bachelor (3 years), Master (2 years) and PhD (3 years)), there are so-called grandes écoles – mostly in the business and engineering fields. To enter a grande école, one must traditionally attend classes préparatoires.
One distinctive feature of these classes prépa is the significance of frequent colles (1 every two weeks per student and discipline – sometimes also written khôlles), which generally consist of 1 hour oral examination, where a couple of undergrads solve a problem in front of an examiner – the so-colled colleur.
Colleurs are mostly professors teaching in classe prépa. However they can also be university assistant professors, high-school teachers, PhD-candidates, or post-doc lecturing on their part time.
Question: What is the most appropriate translation of "colleur" into English?
("TA" or "tutor" both seem too broad in my opinion.)