The Parish, Church and village of St Erth receive their name from an Irishman who lived from 424 to 514 AD. He was Ercus, or Erc, son of Deagh, who had been baptised by the aged St Patrick and then consecrated Bishop of Slane, in Ireland. He was the brother of St Ia and St Uny, who came with him across the Channel to found their respective churches, Ia to St Ives, Uny to Lelant and Ercus to St Erth. His saint's day is October 31st.
At that time ships sailed inland as far as where the medieval bridge now spans the Hayle River, and it was about here that Ercus must have landed. There had been missionaries before him, and the place was known as Lanuthnoe, after Uthinock, another Celt who had founded a "lan", or monastic cell, hereabouts. Tradition has it that a Church was built and that Ercus consecrated it in the usual manner of a 40 days' period of prayer, fasting and preaching, after which it was given the Bishop's name.
Certain it is that the place has been called "St Erth" (variously spelt) ever since.
THE FEAST OF ST ERCUS
The Feast is celebrated on the Sunday nearest November 2. The name of St Erc is associated with November 2nd in the following authorities: The Martyrology of Tallaght (early ninth century), that of Oengus (same date) and the Martyrology of Gorman (3 quarter of twelfth century) which calls him bishop Erc.
Charles Henderson, adjudged to have been the greatest Cornish historian, stated that the connection between St Erth and All Souls can be traced back to the early middle ages. Gilbert Hunter Doble, that great authority on Cornish and Breton saints, confirms November 2.
Davies Gilbert, son of a former curate of St Erth, in his parochial history of Cornwall, 1838, Volume 1, page 366, clearly states that “The Feast is the nearest Sunday to All Souls, November 2. The parish news letters during the time of Parson Mills (1864-86) confirm that the feast was always celebrated on the Sunday nearest to November 2nd.
An ancient rubric of Sarum states: - Commemoration of All souls – No Feast may have office on this day, but if it be on a Sunday, office is of Sunday in the Octave of All Saints, the Commemoration of All Souls being transferred to Monday 3.
So, if November 2 be a Sunday, then Feast is that day, and All Souls on November 3.
So, if November 2 be a Monday, then Feast is on November 1, and All Souls on November 2.
So, if November 2 be a Tuesday, then Feast is on October 31, and All Souls on November 2.
So, if November 2 be a Wednesday, then Feast is on October 30, and All Souls on November 2.
So, if November 2 be a Thursday, then Feast is on November 5, and All Souls on November 2.
So, if November 2 be a Friday, then Feast is on November 4, and All Souls on November 2.
So, if November 2 be a Saturday, then Feast is on November 3, and All Souls on November 2.
Various documents refer to October 31, as the Feast Day of St Ercus. The confusion seems to have started with the notes of William Worcester, in 1478, when he confused the name of Ercus with that of St Herygh whose feast day is October 31. See Canon G H Doble’s Cornish Saints Series – St Erc. Otherwise St Erth Church is remembered at Truro Cathedral on October 30, which was a day prior to 1998, when those parishes which had no fixed feast day (c.f. May 6 –Germoe, June 4 – St Petroc) were remembered.
Trevor Cowls October 02
Catholic Online - Saints and Angels states:
Feastday: October 31
Irish missionary to Cornwall, England, where he evangelized the local area. He is venerated in the village of St. Erth.