Thanks. I am acquainted with Simon Irwin, youngest son of Cyril Frederick Irwin, and thus grandson of John Pritchard Irwin. Simon is keen to trace his Irish roots and has visited Co Mayo where he found a good deal of helpful suggestions but no actual records. Going by the few records that are online, and the citation of George Orme Irwin as John Pritchards father in the Swansea parish register entry for his wedding to Agnes Thorpe, I have tentatively assumed that George may well have been the son of the Irwin Orme marriage in 1816.
The only birth location given by John Pritchard Irwin to census takers was Glenmayo, but usually merely Mayo or just Ireland.
What Simon and I would really like to find are some parish records which would confirm John Pritchard’s parentage.