A mahogany deck box fitted with a brass piano hinge and a simple pressed brass clip-type catch. The box contains a brass drum mounting in the base, shaped to the form of the watch, with a red velvet-covered cork base inside. It has a brass screw-down bezel with silvered site ring and bevelled glass. The lid contains a brass-plated, folded steel label holder for an issue card and a black-painted aluminium label, marked in silver 'MINISTRY OF DEFENCE / HYDROGRAPHIC DEPT. / WATCH CHRONOMETER / Stores Ref. H.S. 527-3636 / Serial No. 28021'. The serial number is engraved through the surface to bright metal.

The bottom of the box is covered with green baize. The silver, open-face case has the winding/setting crown inset into a cylindrical pendant, with a hand-setting push piece on the side of the case to the left at '11 o'clock'. The plain silver, rolled-edge bezel has no fitting for a glass. The silver, screw-down back is machine engraved on the back 'H.S. ­2'. The inside of the back is stamped with the manufacturer's mark 'ULYSSE NARDIN / LOCLE' in Nardin's emblematic shield, the incuse mark 'AIIM' and number '397277', scratched below '901', and, in oval marks '925', the Glasgow import mark (two horizontal interlocking letter 'Fs) with the date letter 'p' (for 1938-39) and in a rectangular mark 'FFBA / 46'.

A white enamel dial of 50 mm Æ is signed 'ULYSSE NARDIN / LOCLE / 28021 / C­W' above the centre, and has a subsidiary seconds dial below. The dial has Roman numerals and the seconds dial has small Arabic ten-second figures. Polished, blued-steel spade and poker-hands have a counter-balanced blued-steel seconds hand.

The going barrel, barred movement is of matt-gilt brass, and is signed with machine engraving on the barrel bridge 'ULYSSE NARDIN / SWISS / ­'. It is also marked on the main plate, by the escape wheel cock foot '28021' in a rectangular surround. A polished steel index, mounted on the balance cock, acts on a horizontal steel screw for fine rating adjustment, the cock having a scale engraved on it with 'F' and 'S' for fast and slow. There is a four-wheel train with a going barrel.

There is a double roller, jewelled and club tooth lever escapement. The impulse roller has a jewelled impulse pin and pallets with red stones, the pallets bank against brass banking pins. The cut bimetallic compensation balance is mounted with 14 brass screws around the rim. The flat spiral, blued-steel balance spring, with over coil, has an index mounted on the upper surface of the balance cock. The train is jewelled to the centre with red pressed-in stones. The balance and escape wheel have polished steel-set end stones.

The instrument is in fine, almost as new condition, with just a few marks on the wooden box.