Cockerell has designed and fabricated marbling equipment, and has been largely responsible for the revival of the art of marbling paper. He is also the inventor of the pneumatic ram used in tooling, the ball bearing fillet, and the tract-guided fillet. In addition, he has contributed to the knowledge of book structure, e.g., the idea of using a free guard around the first and last sections of the text block and also the use of free guards around the folds of vellum sections.
He assisted with the repair and binding of the Codex Sinaiticus , and has repaired and bound several early manuscripts, including the Codex Bezae .
Cockerell is an honorary member of the Society of Scribes and Illuminators, a Fellow of the International Institute for Conservation of Historic and Artistic Works, and a Master of the Art Workers Guild. His publications include Marbling paper, the appendix to Bookbinding and the care of books, and The repairing of books. He has also contributed to several handbooks and encyclopedias.