Principality of Thomond locals. 
Almost all Irish collectors have seen them! Almost everyone with a knowledge of modern Irish history is aware they are not official emissions of the Irish government. I am talking about the stamps of the Principality of Thomond. It seems apparent that they do not represent a particular political party or a suppressed minority. What then is their purpose? (Figure 1).
They are usually seen on the secondary or tertiary market (i.e., E-Bay), thus the profit from sales are not going to a single individual or entity. They don’t appear to send a message, nor do they advocate for a particular course of action. The subjects on the stamps are not necessarily Irish or even European. They appear to be professionally printed in multiple colors, probably by photolithography. They are 30 mm square, but printed as diamonds. The perforations (P 12½) seem professional. The souvenir sheets are imperforate. But why? For what reason? (Figures 2 & 3).
The Principality of Thomond was located in the Shannon River watershed, somewhere in the vicinity of today’s Shannon Airport. Wikipedia describes this as an ancient barony as being in County Clare, and parts of Limerick and Tipperary. The family in power, the O’Brians, lost control in approximately 1542.
The most discussion in the philatelic press was two articles in The Revealer in 1962 in response to an advertisement in Linn’s of 26 February 1962. The September article referenced an Irish Times article reported that Raymond Moulten Sean O’Brien, of 5 Charlemont St, Dublin, was charged by the government for uttering (issuing) and possessing fictitious stamps contrary to several laws (The Post Office Act of 1908 and the Forgery Act of 1913). O’Brien stated in his defense that they came from a Dr. Kessing of New York City, purportedly an observer at the United Nations. Mr O’Brien was convicted. The article seems to indicate the stamps were produced in the United States.
Is there more to this story? If this was a money-making scheme, the amount needed to be sold to show any reasonable return would have had to be large. The amount cited was 901 stamps (or possibly sheets of stamps). There were 12 values and two souvenir sheets. An article in The Revealer in 1996 detailed ten different sets and additional sketches of proposed designs. (Figure 4 is an example of the Churchill Memorial set). Even though the later “issues” appeared as late as 1973, these were overprints on the original 1961 set. The article raised the possibility of another party(s) being responsible for the later overprints. It was later discovered that all twelve values were printed as souvenir sheets. (Figures 5 & 6 shows souvenir sheets of the Churchill set – note blacked-out date on bottom). Even 50 plus years ago, economics ruled. Apparently nothing further has surfaced. Although they are cinderellas, and orphan ones at that, they still appear in the market. Are they interesting? Yes. Colorful? Yes. Collectable? Questionable.
“Correspondence, “Principality of Thomond””, The Revealer, Edit. Walsh, J., (attributed to Dixon, F.), No. 68, May-Jun 1962, p.532.
“‘Principality of Thomond’stamps”, The Revealer, Edit. Walsh, J., (attributed to Dixon, F.), No. 70, Sept-Oct 1962, p.539-540.
“Thomond Locals”, The Revealer, Finn, A. & Warren, B., No. 204, Fall 1996, p.35-36.
Wikipedia, “Thomond”, http://www.Wikipedia.org/wiki/Thomond Edited 31 July 2018, Reviewed 20 September 2018.
The Irish Times, June 28, 1962