Dethick was a scholar and antiquary, and several collections of his heraldic papers survive. He began this manuscript early in the reign of Edward VI and continued it through the reign of Mary into that of Elizabeth I. This was a period of great unrest, with major changes in the state religion, from Edward VI's and Elizabeth's Protestantism to Mary's fervent Catholicism; this is reflected in the appointments to the Order. The first part of the manuscript consists of details of business carried on during meetings of the chapter of the Order of the Garter, followed by a record of the coats of arms of all those appointed to the Order during the period. The names of appointees on this opening consist chiefly of prominent Catholics during the reign of Mary (r. 1553-8), such as Sir Edward Hastings, Sir Anthony Browne, and Thomas Radclyffe, Earl of Sussex; or favourites of Elizabeth I, such as Henry Manners, Earl of Rutland, and Robert Dudley, Earl of Leicester.

The Order of the Garter features in a number of Shakespeare's plays.

Bound in brown calf, with blind-tooled panels, and edges, later (eighteenth century?) gilt bookstamp of Latton of Berkshire and Esher.

Catalogue entry from Royal Treasures, A Golden Jubilee Celebration, London 2002