It is claimed that he was a hermit in the 5th century and lived at Talland between Polperro and Looe.
The parish church of Talland, which is believed to be a 5th-century foundation, is consecrated to him – the only one in Britain.
However, the name Tallanus first appears in documents in the 15th century and there is some evidence to suggest that he was an invention of that period.
Tal = "brow of the hill" and Lan = "holy place" (or church).
Together they perfectly describe the church that the Augustine monks of Launceston established at Tallan (between 1086–1205), and as with other Cornish churches all that seems to have happened is that "saint" has been put in front of a Cornish place name so as to tie that parish to a saint.