The name Ó Seasnáin comes from the gaelic (Irish language) word ‘seasnán‘ meaning ‘one who stands’ – a sentry or guard or defender. Research carried out by University of Limerick scholar, Cathy Swift, has revealed that 17th century manuscripts such as Leabhar Mór na nGinealach record the name as Seastnán. The insertion of the ‘t’ is significant as this may well have influenced the subsequent anglicisation of the name as ‘Sexton’.
We must bear in mind that the Uí Sheasnáin lived in the north Munster area in on the interface between the Gaelic world of the Tuadhmhumhain (Thomand) associated with the ancient Dál gCais and the city of Limerick – originally founded by the Vikings but now occupied by the descendants of the Anglo-Normans and by the new English. Limerick then was an English speaking enclave in a largely Irish-speaking world but because English was the language of power and of commerce, anyone of gaelic origin wanting to progress in this city would have had to adopt the English customs and naming conventions that were prevalent in the city.
It would seem that sometime in the late 1400s/early 1500s, a Seasnán (most likely pronounced sheshtnaun) made his way into the city from his base which was almost certainly either in east Clare or in along the east bank of Lough Derg just north of Ballina. He was quite probably a trader of some sort who had some involvement in the movement of goods along the non-navigable stretch of the Shannon between Limerick and Killaoe. This man was an Irish speaking gael but he would have realised that to progress he would not only have to learn to speak English but to adopt a more anglicised version of his name. In reality, the English speakers of the city had already come to call him by a corrupted version of his name. Either he chose a version of his name that sounded more English or it was chosen for him. In this way Seastnán became Sexton.
This isn’t mere conjecture as a document from 1534 (Letters and Papers, Foreign and Domestic of Henry VIII p.443) refers to ‘Edmund Sexton, alias Sesnan’ a merchant of Limerick. Clearly as late as 1534, the Sextons were still using both the English and the Gaelic version of the name.
It can be presumed that as the century wore on, the Gaelic version of the name fell into disuse in Limerick city. The urbanised Sextons who had become very influential in the city of Limerick must have continued to have ongoing contact with their cousins outside the city walls (not surprising given their new role as merchants who quite possibly controlled trade on the Shannon between Limerick and Lough Derg) as their gaelic cousins for the most part adopted the name Sexton. Perhaps this was to cement their connection with their successful cousins in the city.
During the turbulent years of the late 1500s and early 1600s, members of the Uí Sheasnáin/Sexton family appear to have been dislocated from their base on the lower Shannon and to have become scattered throughout Munster. Some were forced west and a Sessnaine is recorded as holding a small area of land in Emlagh and a Teig Ó Sheasnane is similarly recorded in Cnock in Any (modern Annagh) – both townlands just north of Quilty near Spanish Point in west Clare. Sextons, probably their descendants, are still living in this area today.
Interestingly, the census of 1659 records no fewer than 14 individuals by the name of Sisnane in the barony of West Carbery in West Cork. This would appear to be a version of Seasnán but how the bearers of this name came to be in west Cork is far from certain. It is interesting that they continue to adopt a Gaelic version of the name but it is equally noteworthy that their descendants today are universally known as Sexton rather than as Sisnane or Shasnan or any other corruption of the Gaelic form of the name. This might lead us to believe that the Ó Seasnáin/Sisnane/Sextons who moved south in the late 1500’s or first half of the 1600s were were equally familiar with both the Irish and English language versions of the name.
It is possible that the Sisnanes recorded in West Cork in the 1659 ‘census’ were derived from entirely different stock but this is, I feel, unlikely as it is surely too much of a coincidence that their are considerable numbers of Sexton families living in this same area today. My feeling is that the Ó Seasnain who came south (perhaps connected with the movement of Gaelic armies from the north around the time of the Battle of Kinsale) continued to use the Gaelic form of the name given that they were travelling as part of a Gaelic army and because the area they now found themselves in remained part of the Gaelic world. As West Cork fell increasingly under the influence of the English as the 17th century progressed, it seems likely that they adopted the more English-sounding Sexton version of the name.