Antipodia (OTL Australia) was discovered and claimed by England in 1704 when an expedition went west from Cape Hoorn, (re-)discovering Australia and New Zealand, which were called Antipodia and New Albion respectively. But for quite some while they stayed in the shadow of the English colonies in North and South Atlantis. Only after the latter were lost in the anti-British War, more colonists went there.
1849, the great Potato crisis happened in Ireland. Many of them emigrate to Antipodia, which population more than doubled in short time. Until then, the Irish already had the clear population majority in Antipodia's thinly settled North, South and West, and a smaller majority (60%) in the South-East, but now they clearly outnumbered the English everywhere. The inevitable came in 1850: The Irish rebelled in Antipodia, kicked out the English, who only kept control of OTL Tasmania. The continent was renamed Tir Tairngire (non-Irish people preferred to speak of Tirland, however).
An important development happened in 1856: Until then, the Irish had been under the spiritual rule of the United British Catholic church; but now they had the majority of population in this part of the world and decided to turn the tables. In this year, the first Irish pope (named Patricius I, like all of them) was elected in Antipodia. He announced that "a Time of Humbleness has come for the Holy Roman Catholic Church... now we will live and meditate in the desert, like the old patriarchs and eremits once did, until the day when God decides to smile upon us again". This marked the beginning of the Irish-Catholic church.
In 1896, the Gold Rush in Antipodia / Tir Tairngire happened. The pope decided that the money donated to the church (10% of all founds, plus additional givings by the government and other sources of income) was to be used to adorn the country's churches (like the famous Golden Cathedral of New Dublin, OTL Sydney) and missionarizing in Africa, Asia and later even other parts of the world. The "time of humbleness" certainly had ended.