Although originally in Devon, this church lies west of the river Tamar.   It has always been part of the archdeaconry of Cornwall.  Not only one of the most interesting churches architecturally, but also one of the best documented.  Churchwardens’ accounts can be seen at the Cornwall Record Office.

1. Norman narrow north aisle of c.1200 with round columns and scalloped capitals.  St Mary Arches in Exeter has arcades of similar type.  Cornish Norman aisles survive in part at Lelant, St Clether (rebuilt), St Breward, St Buryan (blocked in), Morwenstow and column sections support an altar table at St Teath.  North Petherwin was a superior church, a fact confirmed by it having chapelries at Werrington and St Giles in the Heath.  It’s place name comes from its patron saint Patern and there is a South Petherwin south of Launceston suggesting that an area called Petherwin may have preceded Launceston.
2. Clerestory of early 14^th century date.  Clerestories, or rows of windows at a high level above an arcade, are now very rare in Cornwall – four or five sites – due to the amount of rebuilding that went on in the late medieval period.  When the north chapel was added in 1518-24 its large windows and much taller monolith granite piers negated the need for a clerestory.
3. South aisle piers of two distinct types of granite.  According to documentary evidence in 1506-11 building accounts, the whiter granite came from Hingston Down near Kit Hill in south-east Cornwall, and the aisle was completed browner granite from Roughtor on Bodmin Moor.  The reason may have been transport costs – Roughtor was 3 miles closer than Hingston Down.  Coarser Bodmin-Moor granite was also likely to be cheaper and more plentiful.  The parishioners paid to open up their own quarry at Rowtor in 1507.  (A similar change to Bodmin Moor granite half way through a building programme can be seen at the Berry Tower in Bodmin in 1508-9).  By the time the north aisle was built the parish were using another Bodmin Moor quarry in Altarnun parish.  Granite was the material of choice in 1500s Cornwall, being durable and producing a nice ashlar finish, see St Ive, Withiel etc
4. Awkward building-break between north chapel and north aisle representing the Reformation.  After this processional aisles were no longer needed.  Brewers of the Procession are noted in 1543-5 and 1558-67 but not thereafter.
5. Waggon roofs with a wall plates with shields in south aisle by John Glanvyle can be compared with Robert Longe’s grotesque faces on the north aisle wall plates.  Strong binoculars and powerful torches recommended for the latter.
6. Base of rood screen, 1518-24.  Carved by three Bretons – Peter Papyas, John Oliver and  William Oliver.  They were paid 24 shillings a foot and may have been undercutting local carvers like those who worked at Stratton for 40 shillings a foot.  Wooden bases for a rood loft St George (like Stratton) was here till 1927.  There were ten guilds here in 1497 – All Hallows, St George, St John, St Luke, St Michael, St Nicholas, Our Lady, St Patern (the patron who also had a store), St Thomas and the Trinity.  There was also a parish group connected with St Christopher.
7. Font with Norman base and crude octagonal bowl replacement.  Building accounts record the removal of the original Polyphant font from the church in 1495-6.  It was probably like Laneast’s font originally – Altarnun-type.  Was the original font accidentally broken during building work?
8. Communion rails from chancel of 1680s date, recycled as tower screen.  These must be by the same carvers who made the 1684 communion rail at Altarnun. 1684.