The settlements in the vicinity of St Blazey were on the highland at Prideaux, the slopes of Trenovissick and across the valley to the heights of Kilhallon. Evidence of this is most traceable at Prideaux, where earthen embankments of a hill fort dominate the landscape with excellent visibility on all sides. Charles Henderson, the Cornish historian mentions, `a triple entrenchment or hill castle, Pridias may well be one of the few instances in which the true name of the earthwork survived: Today this Iron Age fort is still visible, on a wooded spur, consisting of two concentric earth ramparts and part of a third, with diameters 235 metrcs and 160 metres. Remains of a manor house at the farm of Great Prideaux illustrate the convenience of a prime site which would have been in occupation from 500 BC. All along the ancient highland track ways in Britain are evidences of Early Man in the form of hill forts, with burial places called barrows. The existence of barrows may be evident at Garker on the edge of the parish, in the name 'Burrow' field and in Tregrehan where a feature on a 1736 map was marked as 'Little Hill'.
Across the valley from Prideaux on the ridge at the highest point of Kilhallon was another early settlement site. Ditches containing shells, cockles, limpets, mussels, and oysters, have been excavated and a causeway into the site area suggests an imposing entrance at one time, to an enclosure for occupation and safety. There were other `rounds' at Restineas and Carveor, where the name `Car', castle and `Veor' meaning big in the Cornish language intimates another prime site. At Restineas flint arrowheads have been found and at Cornhill farm on the next spur of land to Prideaux, a Greenstone Axe was found. On St Blazey moor prehistoric wooden picks were found and at Trenovissick three bronze axe heads were unearthed when building development took place.
The next evidence of the early history of the area is the Biscovey Stone. This is the shaft of a Celtic cross inscribed on one side and erected to the memory of a king of British descent. lt is called the St Blaise cross in 1725.
It is a Christian monument, the inscription and ornament indicating that it was erected in honour of an important person. It was sited originally on the south side of the St Blazey to St Austell road near the corner past Biscovey Post Office. In 1726 it was described as `a fine old monument that had been erected and inscribed around 600 AD to show the Saxon advance into the county.' Arthur Langdon's account of Cornish crosses records that in 1870 the head of the cross had been missing for 200 years perhaps as the result of the Reformation in England when many religious monuments were destroyed. Dr Borlase in 1754 assesses its age from around 900 AD and also records that, `in a little meadow near the place where this stone now stands many human bones have been found and I suspect that this cross may have been removed from thence: Perhaps this is a reference to the cemetery linked with St Werry's Chapel?
The shaft remained by the roadside, acting as a, Biscovey gatepost for a field near the tollgate, the St Blazey turnpike gate. The holes for the bars can still be seen. In 1896 it was removed by the Reverend D R Vaughan and erected in its present position alongside the South door of St Mary's Church, Biscovey.
A Celtic cross was often erected by a chapel or oratory and there is evidence that a chapel existed in this area called St Werry. In 1568 Queen Elizabeth I sold to Edward Gruniston a chapel with a small cemetery and a house called the Store (or Stow) House annexed to it, in the parish of St Blaise. It would seem that a chapel originating from Celtic days had survived to that time. Charles Henderson in a letter to the vicar of St Blazey in 1926 described St Weryes as a chantry chapel within the limits of the parish. He enquired whether any field called `Chapel Close' or some such name existed and thought that it would be `rather a find', if the site of St Weryes could be identified!
The Lanhydrock Atlas, a mammoth edition of maps of the Robartes estate compiled in 1696, contains a map of the Biscovey tenement. It shows two fields called Great Chaple Park and Little Chaple Park! These fields are between the lane leading to Whitewater and Tregrehan, and the road to Luxulyan at Leekseed Chapel probably an ancient trackway to Luxulyan, another Celtic site. The Reformation destroyed many private chapels. These had been licensed in Cornwall by the Bishops of Exeter from the thirteenth century. The second earliest to be licensed in Cornwall was in 1283 at Boswythgy (Bodiggo) in Luxulyan parish, where the late husband of the present owner recalled walls and window tracery of a chapel in his young days.
The Domesday Book compiled in 1086 to record all land in England for William I has mention of two manors which would fringe on the land where St Blazey later developed. The whole district would have been rated under Tywardreath, with Bodiggo a little further inland. Tywardreath was the larger manor with six acres of woodland and 100 acres of pasture - Bodiggo had one league of pasture. The value of the manor of Tywardreath before 1086 was £4, whereas Bodiggo rated 40s and the assessment by William's men rated Tywardreath at 40s and Bodiggo at 30s. Between these two manors and Towan in St Austell area there was no other recorded.
The records of Tywardreath Priory reveal that in 1187 a corn mill was established at Ponts Mill. The sea and river estuary extended to Ponts Mill and it served as a small port. As late as 1720 vessels of 80 tons were able to reach there but by 1800 silting from alluvial deposits prevented access by sea this far.