The history department at Cottenham Village College has one more member than you might expect. Ruth Brown is a teaching assistant (TA) and one of the longest-standing members of the department, and this article is about how her work has an impact on specific pupils, whole classes and teachers. The key factor is that Ruth has excellent subject knowledge. She reads history books-- and brings her learning to the classroom, sharing the historiography with the students. Ruth's status in the history classroom is that of being not-the-teacher--and she models "knowing a lot about history" and "reading history books" as positive things which people who aren't history teachers might do. As good TAs do in every subject, she helps to form a bridge between the teacher-expert and the students. The article is also about the way in which the department works to allow and encourage her to operate. It is clear that the whole department has a culture of mutual trust and shared purpose. This is the kind of trust which enables students to carry on arguments across GCSE sets, using Ruth (the only person to attend multiple Year 10 history classes) as the intermediary. It is the kind of trust which is based on honest feedback. The students, ultimately, are the ones who benefit. The voices of various members of the department--Ruth included--can be heard through their words in this article, the central figure of which is a "recipe for a Ruth", consisting of a series of good ideas both to get the most out of the TAs who come to your lessons and to build a vibrant departmental culture. The quotation from Milton used as part of the title expresses how highly the history department at Cottenham value their Ruth--can you find your angel?