The parish of Sithney, (Cornish: Merthersydhni), is situated in the Deanery and Hundred of Kerrier. It is bounded on the north by Crowan, on the east by Wendron and Helston and the Looe Pool which separates it from Gunwalloe, on the south by the sea, and on the west by Breage. It is named after the patron saint of the church, who chose to be the patron saint of mad dogs (in preference to young women). The parish lies about three miles north west of the town of Helston in a mainly agricultural area. In the 19th century there were at least eight tin mines in the area, none of which are working today. There are the ruins of an old farmhouse Plane-an-Gwary, meaning 'place of the plays'. Here Cornish Miracle plays were acted in medieval times, and later Cornish wrestlers were seen here on feast and fair days.
The principal villages are the Churchtown, Porthleven, St Johns, Penrose, Mellangoose, Lower Prospidnick, Dowga, Sithney Common, Sithney Green, Coverack, Crown Town (or Gudna), Lowertown, Chyreen and Lower Tregadjack. Porthleven, which was originally part of this parish, became a separate parish in 1844.
Most parish and church description(s) on these pages are from Lake's Parochial History of the County of Cornwall by J Polsue (Truro, 1867 - 1873)