The growth of the popularity of a saint is often influenced by the “external factor” — the cult is provided support from outside, both from the local authorities and the rulers of neighbouring regions. This article focuses on the life and martyrdom of two holy virgins, presented in the vita of Saint Beuno, whose cult in medieval Wales was the second most popular after Saint David’s of Wales. The main events of their lives coincide in many ways: both girls came from noble families, both had been decapitated, both were raised from the dead and turned toward monastic life by Saint Beuno. However, the traditions of their veneration subsequently evolved in different ways. The relics of one of them, Saint Gwenffrewi, in the 12th century were moved from the resting place of the saint, a small parish of Gwytherin in northern Wales, to Shrewsbury Abbey, and churches consecrated in her honour could be found even in the bordering English counties, while the other, St. Tegiwc, in fact, remained unknown even in the “native” country. The aim of this study is to elucidate the role of “external forces” that are not related to the local monastic community in the development of very local Welsh cults. The similarity of the “initial data” in the stories of both saints allows us to leave them outside the scope of the comparative analysis, focusing on the factors affecting the cult from the outside. In the first case, the interest shown by the English clergy in the little-known Welsh saint contributed to the spread of her popularity far beyond the place where the original cult appeared. In the second case, it was precisely the lack of support from the secular authorities that prevented Saint Tegiwc from becoming known outside the parish. It is relatively recently that the topics concerning the organization of the church on the territory of the Welsh kingdoms, the cults of the Welsh saints, as well as the texts linked with them have been addressed in the historiography. The future clarification of these issues will add new values to the portrait of the national identity of the modern Welsh.