The identity of St Senan is uncertain but there is reason to believe that the famous Irish Saint Senan was the original patron of this parish and possibly of Plouzane in Brittany. It is possible that Senan of Scattery (Inis Cathaig), founder of many churches in Ireland, in the sixth century visited West Cornwall on his way to Brittany. Ireland was not beyond the reach of Sennen fishermen in the past, nor Brittany either.
From the beginning of the parochial system after the Norman Conquest both Sennan and St Levan were separate civil parishes, though from an unknown early date both parishes were ecclesiastical dependant on the Royal Deanery of St Buryan. Since St Buryan was a "peculiar" neither Bishop not Archdeacon had any jurisdiction in the three parishes. (See the file on St Buryan)
1430-From the registers of Pope Martin V it is learnt that on February 21st the Pope delt with a recent partition sent to Rome by the inhabitants of Senan in Cornwall. They had told him that within the limits of the parish church of St Buryan there had formaly been built a chapel of St Senana, with bell tower, bells and baptismal font, and that the chapel was accustomed to hear mass and to enjoy the ecclesiastical sacraments, except for burial. instead of going all the way to the parish three miles distant , they begged the Pope to give them licence to make a cemetery around the chapel and to have it hallowed by some Catholic Bishop. They urged that as their village lay on the sea shore they could not accompany their dead all the way to St Buryan lest their homes be raided by pirates and enemies in their absence. This partition fixes the date of the present south aisle, arcading, tower. and font before 1430.
1420-1425-Edmund Lacy
1448-"Commission because of the Bishops own age and infirmity to John Bishop of Clonfert to consecrate Sennen Chapel in the parish of St Buryan"
1655-The seventeenth century brought increasing non-conformity and in consequence parochial unrest. A group of Lands End Quakers was founded this year. They refused to pay tithes, attend church or swear oaths which led to severe reprisals.
1775-Dionysius Williams died and is buried opposite the tower.
In the eighteenth century accounts show payments made for example to shipwrecked sailors; for repairing roof slates; for the singers and beer on ringing night. And in this year the sum of £3.2.0 spent on a "barrel of powder" promised the expected French invasion a hot reception.
Records for the following fifty years reflect a depressing tale of neglect and non-attendance.
1816-1826-William Spry curate served both Sennen and St Leven. He lived in Penzance travelled to his cure on "the wooded horse" or velo .