At the beginning of the 19th century it had become obvious that the magnitic compasses in use in H.M. Ships were of inferior manufacture and efficience. In a Minute to Their Lords Commissioners of the Admiralty dated 15 July 1837, Captain Francis Beaufort, the hydrographer of the Navy, drew attention to this deficiency and suggested the Their Lordships agree to the setting up of a Committee of Officers to consider the whole subject of design and manufacture of these highly important navigational instruments. With commendable speed three days later, on 18 July, Their Lordships wrote to Captain James Clark Ross the discoverer of the north magnetic pole; Major Sabine a specialist in terrestial navigation and later President of the Royal Society; Samuel Hunter Christie professor of mathematics at Woolwich Royal Military Academy; Captain Thomas Jarvis later Surveryor-General in India; and Commander Edward Johnson and Captain Beaufort asking them to attend a meeting to be held in the Admiralty library six days later on 24 July. At this meeting these officers formed a very important body known as The Admiralty Campass Committee and for the next three years they investigated every aspect of magnetic compass manufacture and design. Their findings were that from experiments carried out during this period, by far the ADMIRALTY PATTERN ONE COMPASS and in their report submitted on 29 June 1840 they recommended the manufacture and purcase of twelve such compasses for further trials. Choosing a suitable manufacturer posed problems and eventually an order for 200 was placed with William Gilbert of 25 pounds each. However when Gilbert died in 1844 only forty had been completed. Consequent upon his death the contract was given to Henry Barrow and he held the monopoly for the manufacture and repair of the Admiratly Pattern one compass until the 1880's after which no more were made.

Although the compass offered for sale is unsigned, the diameter of the card (7½in); its mica and paper construction; the sizes and shape of its four "edge bar'" magnetic needles; the dividing of the inset 360 silver scale and its associated verniers on the azimuth ring and the construction of the azimuth ring itself show that "No 27" accords with the Compass Committee's recommendations of 1840. The absence of a manufacturer's name is almost certainly explained by the fact that the engraved plates for printing the compass cards were provided by the Compass Committee and it would be highly unlikely that this would have included a manufacturer's name; however, incorporated in the ornamental fleur de lys marking the North cardinal point is the naval crown, a mark which usually distinguishes compass cards made for the Royal Navy. (See illustration)