General Masonic reference works on the Societas Rosicruciana in Anglia document the society's College based administration of its First Order, Grades I through IV, as a matter of public organizational record, distinct from any ceremonial content the society transmits only to its own members. Zelator's place within that four grade span is part of the same published structural material.
Published histories of the SRIA and the Hermetic Order of the Golden Dawn both document the direct borrowing of grade names and Tree of Life style numbering from the SRIA's earlier sequence to the Golden Dawn's later First Order, a lineage general reference works treat as one of the clearest documented cases of one nineteenth century esoteric order's structure shaping a later, better known one.
As with every grade in this family, what is publicly documented is the society's administrative structure and the historical lineage between the SRIA and the Golden Dawn, not the specific ceremonial content either order transmits only to its own members.
General reference works on both societies note that the SRIA continues to exist as an active, Masonic-Rosicrucian body in its own right, its First Order grades, Zelator among them, still conferred under the same College based administration documented since the society's 1866 and 1867 founding.