I note that several CS Lewis scholars disagree with Michael Ward's thesis. Will Vaus was originally convinced and then decided against it, for example. I have read their arguments only in summary, and they raise valid points. However, I can already see at least one weakness in their arguments. I may address that in general at some future date even before I have read their criticism in full, or I may hold off. But it should be interesting to follow up on.
The weakness, in brief, concerns a misunderstanding of the creative process of telling a story. Both Devin Brown and Vaus make assertion that imposing multiple structures on a story and letting the story tell itself do not likely coexist in the same work. Put that way, they might say I have overstated their case and disagree that they have said this. I nonetheless think they have, and I think it misguided.