This is a description of the methods used to successfully refurbish and preserve the anchor lost from HMB Endeavour (Lieutenant James Cook) off the coast of Queensland in 1770, and recovered in 1971. The anchor was shown to be in a very sound structural condition, enabling a successful restoration to be carried out, using an electrolytic (cathodic) treatment in a sodium hydroxide solution. Other aspects discussed are (1) the philosophy and requirements of cleaning and preservation methods for old cast and wrought iron objects, (2) the historical circumstances of the anchor loss, and its recovery, (3) its authentication, (4) the practical methods and materials used in the restoration, (5) the design of anchors in that era, and a likely constructional method based on radiographic examination, as seen against the technology of the time, (6) compositional and metallurgical aspects, (7) the unexpectedly low corrosion rate, and (8) descriptions of the various artefacts found during cleaning of the anchor and stock hoops, e.g., the anchor markings, stock wood fragments, ring canvas, paint remnants, and stock pin and nail remnants. The anchor was completed by the fitting of a replica wooden stock made by the Department of Transport.