I'Anson has to be the very worst name to research! Just look at the mis-spellings I have found:
The Oldest Written Form of Our Name
The Latin-alphabet letters I and J were not systematically distinguished until the 17th century. In early documents, therefore, the letters I and J were interchangeable, thus the name IANSON or I'Anson appeared as Janson or J'anson. Transcribers of early documents, usually people unfamiliar with the name and its pronunciation, almost invariably write the J instead of the I, indeed, a few even use an L (L'anson), assuming the name to be French. At least one branch of the family officially adopted the name Janson when they moved to London from Yorkshire.
Pronunciation seems to have been the cause of some variations in the spelling of our name: some branches of the family say "Eye -anson", some "EEan-son" and some "Ine-son". In an age of general illiteracy it would have been the job of the cleric of the parish church to try to write the name appropriately, based on the pronunciation.
Thus, we find our family referred to variously as Janson, Jansonn, Jansonne, Jainso, Jenson, Ienson, Ianson, Eyanson, Ainson, Ineson, Hineson, Hinson, Iveson - - and more. This makes the researching of the family ancestors a difficult task.
We have yet to determine the source of the name, but we generally think that it is of Scandinavian origin, possibly a contraction of a name like Johannson (a very common Scandinavian name, akin to Johnson). The name JANSON is found in the Netherlands and even in France (though it is rare there, probably arriving with the Norse settlers who became the Normans). Bryan I'Anson, in his "History of the I'Anson Family" (1915), claims a French noble origin, but this seems unlikely and his sources for this assertion have not yet been found. In the Orkneys there are many with the name EUNSON that claim Viking ancestry, and this name, too, may relate to ours.
The biggest mystery is where the apostrophe came from. It seems to have been used consistantly by the literate members of the family in the 17th century. Could this have been its original spelling? -- or an aid to correct pronunciation? -- or just an affectation?
quoted from www.surnamedb.com
A Variant Spelling from Fingall?
Amongst many variations in the spelling of the I'Anson name, one is particularly interesting, the spelling EYANSON, because from it may have sprung a branch of the family that still bears that name.
Between 1690 and 1698, the church official responsible for recording births, marriages and burials in the parish register of the church of St Andrew in Fingall (or Finghall), always wrote the I'Anson name as Eyanson. Bear in mind that all the villagers were probably illiterate and only knew the sound of their name and not its spelling. Consequently, the clergy would have written the name phonetically, based on its sound. After 1698 the spelling in Fingall changed to Ienson before returning to Ianson/Janson.
There was no new Rector for St Andrews in that decade -- a Robert Smith was Rector from 1665-1710 -- but perhaps different clerks were responsible for keeping the parish registers up to date. This would be revealed by an examination of the register itself (or a microfilm of it).
Nowhere else in English records have I found the I'Anson name written as Eyanson other that in this brief period in Fingall. However, the name Eyanson appeared in the 18th century in the U.S.A. According to family tradition, John Eyanson (born c.1725) emigrated from Dublin, Ireland to Baltimore, MD, U.S.A. in 1742. A 1988 search of some of the records for Dublin disclosed another Eyanson family, but the relationship to John Eyanson's family is not yet known: a Jacob Eyanson and his wife, Mary, had a son, John (born 1744) which is documented in Dublin records.
I have a theory that a young I'Anson from Fingall decided to travel to Ireland in the 1690s taking with him a letter of reference from his local vicar or church clerk. This churchman always spelled the I'Anson name EYANSON (as we see in the Parish Register for that time), thus the young man would have accepted this as the standard spelling of his name, and it would have been copied onto all his documentation. There he had a son John c.1725 who emigrated to the U.S.A., and possibly also another son, Jacob.
NB: On searching Eyanson on the I.G.I. (Family Search website of the Church of Jesus Christ of the Latter Day Saints) I find my Fingall theory shot to pieces -- there were, in fact, Eyansons recorded in London as early as 1677. However, there are only 8 Eyansons recorded there in total, an indication that this is an unusual spelling of the name.
Descendents in U.S.A. of John Eyanson from Dublin have a web site that may be of interest:
a West Yorkshire Variant