St Erth (Cornish: Lannudhno) is a civil parish and village in Cornwall, England, United Kingdom.The village is four miles (6.5 km) southeast of St Ives and six miles (10 km) northeast of Penzance.St Erth takes its name from Saint Erc, one of the many Irish saints who brought Christianity to Cornwall during the Dark Ages, and is at the old crossing point of the River Hayle.