Gerald Gardner's Bricket Wood coven, active in England from the early 1950s, worked a three-rank system of initiation that became the structural backbone of the Wiccan revival. A First Degree initiate is admitted to the Craft itself, usually by a High Priestess or High Priest already standing within an unbroken chain of initiation reaching back, by the tradition's own account, to Gardner. Second Degree marks a working priest or priestess capable of leading ritual and, in time, hiving off to found a new coven. Third Degree, historically conferred through a rite involving symbolic sexual polarity between High Priestess and High Priest, marks full clergy status and the right to initiate others in turn.
Each degree carries written material, commonly called a coven's Book of Shadows, copied by hand from initiator to initiate and understood as oath-bound: material a Gardnerian or Alexandrian Witch has sworn not to disclose outside the circle of the initiated. What can be said publicly is the fact and structure of the transmission, not its wording, and lineage covens have generally held to that line even as outsiders published material claiming Gardnerian or Alexandrian origin.
Alex and Maxine Sanders built Alexandrian Wicca in the 1960s on the same three-degree frame, initiated, by Alex Sanders's own account, into Gardnerian lineage before establishing a parallel line of covens across Britain and, through their students, internationally. The two traditions remain close enough in structure and material that practitioners often describe them as siblings rather than as separate systems, distinguished more by emphasis, Alexandrian covens leaning further into ceremonial magic, than by the underlying degree structure itself.