Peaked cap of blue wool with cap band of black webbing, belonging to a Chief Petty Officer/ Engine Room Artificer 3rd Class. The cap badge is worked on blue wool and features a red velvet crown embroidered with metal thread. There are two branches of metal thread-work laurel leaves surrounding the crown with a metal anchor below with silver purl work. The visor of the cap is of black patent leather with a strap of the same above it secured to the cap at both ends (which correspond with the edges of the visor) with buttons covered with black sateen.

The underside of the visor is lined with green leather. There is an interior cap band of brown leather and the cap is lined with blue silk which has been machine stitched in concentric circles. There is a cloth label stitched inside the cap with the following inscription in black ink: 'E.T. BONNOR/E.R.A. 2730'.

Edward Thomas Bonnor was an Engine Room Artificer 3rd Class. This rank was equal to certain Chief Petty Officers in the military branch of the navy. In the early 20th century there was an increased concern that the technological expertise of the Royal Navy was not comparable to that of Imperial Germany. A training scheme was established for boys who were trained as apprentices at Chatham, Portsmouth and Devonport. When an artificer entered the navy it was usually at the rank of Engine Room Artificer 5th Class. This meant that the boy had to complete the last phase of his training at sea. Engine Room Artificers of 3rd Class and above were very well paid, as their expertise was highly valued.