I'm puzzled as to why Jackson attributed IRH to John Irish as no other Irish silver reference book does so. Likewise, I cannot trace any source for J.R.H (JRH) being attributed to him.
Bennett attributes II in an oval reserve and II in a rectangular reserve to John Irish while Dudley Westropp mentions a spoon he owned with [crowned] 'I.I' 'I.IRISH' [crowned] 'I.I'. The authors of Cork Silver and Gold shown a mark [crowned] 'I.I' 'I.IRISH' 'I.IRISH'. Cecil C. Woods does not mention John Irish in his 1895 list The Goldsmiths of Cork.
'I.IRISH' and [crowned] 'I.I' often appear on the same piece of silver or even [crowned] 'I.I' 'I.IRISH' [crowned] 'I.I' as on Westropp's spoon and another sold in 2003. This would seem to indicate that the [crowned] 'I.I' is not an older mark of John Irish as suggested in the Irish Provincial section of this website but commonly used in association with 'I.IRISH'. Also found is 'I.IRISH 'I.I' 'I.IRISH. These combinations are the ones most commonly seen on John Irish silver. Did John Irish even use a STERLING or STER punch as it's not mentioned or shown on any silver by him I've come across? If anyone has a photograph of such a mark, please post it. On the other hand, STER does appear on spoons with the maker's mark JRH which suggests to me this is not a mark of John Irish despite what some sellers may say.
The Sisters of Loreto in Ireland commenced with the setting up of Loretto Abbey, Rathfarnham in 1821.The change of spelling from 'Loretto' to 'Loreto' is explained below.
In November 1821, M. Teresa Ball and her two companions, M. Baptist Therry and M. Ignatia Arthur, returned to Ireland to establish the Institute of the Blessed Virgin Mary in Ireland. In 1821, Dr Murray purchased the dilapidated Rathfarnham House, but it was not fit to be occupied until 4 November 1822. On occupation a boarding school, convent community and free school were opened for Catholic girls. Rathfarnham House was renamed, ‘Loretto Abbey’, after a shrine to the holy family in Loreto, a small town near Ancona, Italy. The spelling changed in the early 20th century to Loreto. Loreto Abbey remained the ‘Mother House’ of the Institute in Ireland, and its dependent foreign houses until 1976.
The Fermoy community seems to have started in 1853 as per link Argentum quoted.
The decoration on Jo's spoon (or at least the 'Loretto' inscription) cannot be by John Irish whose working life is given as 1748-75 (Westropp & Cork Silver and Gold), 1748-80 (Bennett). Bright cut decoration like this appeared on Irish silver up till about 1810.
So, it would seem that Jo's spoon was inscribed 'Loretto' at a much later date that the bright cut style of the spoon suggests but as to who JRH was, I am no wiser.