I thought you might be interested. In 1944 Tolkien wrote this to his son Christopher:
Priscilla... has been wading through the Ballad of the White Horse for the last many nights; and my efforts to explain the obscurer parts to her convince me that it is not as good as I thought. The ending is absurd. The brilliant smash and glitter of the words and phrases (when they come off, and are not mere loud colors) cannot disguise the fact that G.K.C. knew nothing whatever about the "North", heathen or Christian.
And, as a side note: C.S. Lewis knew much of The Ballad of the White Horse by heart!