This place-name, together with Henllan Owen Uchaf and Isaf may denote the site of an early medieval church. According to local tradition, an early church belonging to Eglwyswrw parish was sited in the vicinity; although it is thought that name `Henllan? could refer to the Iron Age hillfort of Castell Mawr some 500m south-west of Henllan, which could have been reused in the early medieval period. Henllan may have been the predecessor of St Christiolus? Church (NPRN 403566).

Sources include:
Cambria Archaeology, 2003, Early Medieval Ecclesiastical Sites Project, Pembrokeshire gazetteer

N Vousden, 30 November 2017