It is important to note that Catholicism in England pre-dated any missions from the Bishop of Rome and when Augustine of Canterbury arrived on a papal mission, he found many Celtic bishops who considered themselves fully Catholic and in full communion with the rest of the church. Catholicism in Britain pre-dated Papal claims in the same sense that it did in the eastern Orthodox world. The suppression of Catholicism by the protestants was not limited to severing ties with Papal authority but focused on the elimination of the sacramental form of worship, the Mass, the Saints, fasting, the Christian calendar - anything which the protestants linked to Catholic “superstitions”.
The point of this is that Anglo-Catholicism continued to exist under Protestant ecclesial rule and achieved a significant revival during the Oxford movement. Anglo Catholics and Anglo Protestants share many traditions from their common period, but it seems unlikely that their pathe will remain eclesiastically in common. With the current implosion of much of the Anglican communion the evangelical protestants are simply moving in one direction and the traditional Anglo Catholics in another.
So, if the author is simply arguing that the Church of England and Kate Schori and Vicky Gene's Episcopal Church are protestant, there is no argument. If he is arguing that the continuing Anglican churches are not part of the Anglican communion, he is also correct. We are not in communion with the CofE or TEC. However his claim that Anglicanism is not Catholic is simply historically ignorant. Only protestant Anglicanism is protestant, and even protestant Anglicans run the gamut from those who are similar to Luther to full bore Puritans to New Age Wiccans, Spongian agnostics and apparently, one Muslim priestess.
Tell that to John Henry Newmann, probably the most prominent Anglo-Catholic that Britain ever produced.
I'm not sure what this prof's particular motive is in publishing this screed, but he is totally dishonest about the historical background, and that's enough for me to write him off right away.
Like several other posts here, I'm trying to understand what you mean by the very broad word "catholic." Do you mean Roman Catholic?
Or catholic in the sense as part of the universal Church?
Celtic Christians definitely knew themselves to be in communion with the universal church, but as defined by Rome, that is under the control and submissive to the Bishop of Rome? Did not "Catholic" in the 5th Century mean something quite different than it meant just a couple hundred years later? Importantly to their day, they even used a different Church calender--which had to be worked out before the agreement at Whitby Abbey in AD 664, usually seen as when the Celtic/English Church formally submitted to Rome.
When I substitute "universal" for "Catholic" in your post it contradicts itself and makes little sense. When I substitute "Roman Catholic" for your word "Catholic" it also makes no sense. Perhaps you mean by "catholic" a pattern of worship?
Don't Anglo-Catholics consider evangelical Anglicans part of the Church catholic?
If by "Protestant" you mean the puritan/reformed wing of Anglicanism things make more sense. Last I checked though, the Puritans are all dead, or Presbyterian, which of course though sometimes difficult, shouldn't be confused.