In 1801 the population of Illogan Parish (now St Illogan) was 2895. By 1811 it had risen to 4078, with much of the increase in the area of Pool, a growing centre of mining and associated industry. Because of the distance from the parish church the spiritual needs of Pool were met by a new chapel-of-ease built on the “West Field” of Treloweth Wartha Farm. This field, together with 20 acres of adjoining enclosures had been purchased in 1801 from Lord Falmouth by Lord de Dunstanville of Tehidy Park, who financed the building of the chapel, gifting it to the parish together with the rent of the remaining land (£42 per year).
Treloweth Chapel , as it was first known, was consecrated on 6th July 1809 by Dr Pelham, the Bishop of Exeter, who had spent the previous night at Tehidy House. Present were Lord de Dunstanville, the Honourable Miss Basset (his daughter) and the Misses Mary and Catherine Basset (sisters). After the ceremony a large party, including the reverend gentlemen, dined with Lord de Dunstanville at Tehidy.
Among church papers examined some years ago was an undated handwritten note stating that the chapel was consecrated in the name of the Chapel of Illogan or Illogan Chapel although later, during the rebuilding of the Parish Church (see Parish Church history on this web site) it was referred to as the Chapel of Illogan or Chapel of Trevenson. The note also referred to it being known as Trevenson Church or Trevenson Chapel of Ease.
By a deed of 1809 Lord de Dunstanville covenanted for himself and his heirs to keep the chapel in repair. In time there arose a resistance from later Bassets to do so and payments ceased in 1915
1890. The inside of the church has been decorated, perhaps for Harvest Festival. The pulpit appears not to be the one now in use