Hi I can’t answer your question specifically except to point you in the direction of John Lucaks, a huge admirer of the man , who wrote often of him. There is specifically one book called Churchill: Visionary, Statesman, Historian.

As an aside, William Manchester was also a huge fanboy of the statesman, and was in awe of his writing. He spoke of this in the first volume of his autobiography, which went up to about 1930.