Eglwysilan parish was a geographically large parish centred on the hamlet of the same name. It still exists, but is much smaller these days. It has included, amongst other places, the towns and villages of Caerphilly, Abertridwr, Senghenydd, Nantgarw and Cilfynydd. These are all places where my ancestors have lived.

The parish population expanded with the opening of mines in the area and this work is what brought two of the three THOMAS families in my data to the area. It also resulted in the parish eventually being carved up into several smaller ones.