It is anti-Catholic, but it is interesting to read.
Here are two quotes from it:
"The monks sent to England [in 596 A.D.] by Pope Gregory the Great soon came to see that the Celtic Church differed from theirs in many respects…Augustine himself [a Benedictine abbot]…held several conferences with the Christian Celts in order to accomplish the difficult task of their subjugation [submission] to Roman authority…The Celts permitted their priests to marry, the Romans forbade it. The Celts used a different mode of baptism * from that of the Romans…The Celts held their own councils and enacted their own laws, independent of Rome. The Celts used a Latin Bible * unlike the [Roman Catholic’s Latin] Vulgate, and kept Saturday as a day of rest.” (A.C. Flick, The Rise of Medieval Church, p.236-327)
“It seems to have been customary in the Celtic churches of early times, in Ireland as well as Scotland, to keep Saturday, the Jewish Sabbath, as a day of rest from labor. They obeyed the third commandment literally upon the seventh day of the week.” (James C. Moffatt, D. D.,The Church in Scotland, Philadelphia: 1882, p.140)
Due to the world of Patrick’s day knowing the truth about him and the Celtic Church, Rome made no mention of, or claim to, Patrick until at least 200 years after his time. Bede did however make record in 431 A.D. of an attempt of a Roman Catholic missionary to bring the Celtic assemblies under the rule and doctrine of Rome:
"Palladius was sent by Celestinus, the Roman pontiff, to the Scots [Irish] that believed in Christ." (Bede, Ecclesiastical History, p.22) But "he left because he did not receive respect in Ireland" (William Cathcart, D. D., The Ancient British and Irish Churches, p.72).**