The old King is actually the new Prince, while the old Knight is the new King. Aleister Crowley understood this obscure symbolism. So that no misunderstanding be made, when he designed his own Tarot deck during World War Two (known as the Book of Thoth in emulation of the French Tarotologist Etteilla) Crowley retitled the Golden Dawn names as Knight, Queen, Prince and Princess. For the real secret was that the old King equaled the new Prince and not the new King. Very difficult to understand and very obscure indeed. But nevertheless the real secret of the Golden Dawn Tarot system.
This symbolism is clear enough in Regardie's original "Golden Dawn" book, but it became an unintentional blind in "The Complete Golden Dawn System of Magic". For Regardie's coeditor Christopher Hyatt did not comprehend this bit of esotericism as well. Historically Arthur Edward Waite understood it when he composed his famous Rider-Waite deck. But Paul Foster Case did not understand this subtlety (as revealed in his private writings titled "The Oracle of the Tarot"). In terms of contemporary authors, David Godwin understood the real order, and has revealed it in his Cabalistic Dictionary. And all of this is fully clarified in the twelfth key to "The Western Mysteries" under the sub heading "Allocation of the Court Cards" (found on page 309).