It takes its name from the 5th-to 6th-century Saint Grwst, the site of the original church dedicated to him was Cae Llan in Llanrwst (land now occupied by the Seion Methodist Chapel).
It takes its name from the 5th-to 6th-century Saint Grwst, "church or parish"llan "of St Grwst". The site of the original church dedicated to St Grwst was Cae Llan in Llanrwst (land now occupied by the Seion Methodist Chapel).