It is said that there are five modern spellings of this old Irish name, these being Sherrin, Sheeran, Sheerin, Sheryn, and Sheran. Originally recorded as O'Sheeryne and O'Sirin, the name is one of the famous examples of an Anglo-Norman family (originally Prendergast) who 'gaelicised' themselves in the 15th century. However there are few absolute certainties about any surname, and for this one - none at all! As O'Sirin the name seems to have been prevalent in County Cork in the 1600's and yet by the 18th century the name is apparently extinct in that county. It seems that thereafter it is to be found mainly in the counties of Derry, Fermanagh and Donegal in Ulster, about as far away as it is possible to be from Cork. This does suggest that as the Ulster spelling was usually O'Sheerin, that we may in fact be dealing with a totally different and unrelated clan. To add to the confusion some of the Ulster 'Sherrins' may have an English origin, the name being derived from the olde English 'scirwine', a nickname for a fast runner, one who moved as quickly as the wind. What is certain is that there are many quite early (by Irish standards) recordings of the surname, and these include Katherine Sherrin, who was almost certainly of English origins, christened at the church of St John the Evangelist, Dublin, on July 26th 1655, Anne O'Sheeryne who was christened at Derry Cathedral, Templemore, on February 12th 1656, and Alice, the daughter of James Sheran, christened at Six Mile Cross, County Tyrone, on February 23rd 1864. The first recorded spelling of the family name is shown to be that of Thomas O'Sirin, which was dated 1606, born at Cork, County Cork, during the reign of King James 1 of England and V1 of Scotland, 1603 - 1625. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.