I don’t know details of his views, but my advisor spoke of him as being in the general “Liberal Catholic” camp of people like Charles Gore. Historically that basically meant the kinds of ideas about the Bible and Christology that conservative Catholics criticize in scholars such as Raymond Brown, and a view of doctrinal development that respected tradition but was open to more change and development than orthodox ('Roman") Catholics would be comfortable with. I say “moderately” because I don’t think he would have questioned the basic creedal affirmations of the Faith. However, I don’t know much about his views–I was generalizing on the basis of vague statements of my doctoral advisor, who is well informed about such matters.
I wish now I had not used the phrase! I did so because I wanted to note that he was Anglo-Catholic (i.e., that he would have considered his perspective to be Catholic), but that he would be coming from a more liberal perspective than most people on this board. It clearly caused more confusion than it removed, however!
One note–I checked the Wikipedia article on him and it says that he was very active in ARCIC–the Anglican-Catholic dialogue. He said that ecumenism was “a good cause to die in,” and I second that sentiment entirely!