Commander Derek Howse, who has died aged 78, was a man of many talents which he used unstintingly in time of war, and in times of peace for the public benefit. After a distinguished career in the Royal Navy he joined the Museum service, and rose in it to become the leading authority on the history of the buildings, instruments and astronomical timekeepers of the Royal Observatory at Greenwich, on the solution in the eighteenth century of the problem of determining the longitude at sea by lunar distance and by chronometer, and on the development and use of radar at sea.

Derek was the son of a Captain of the Royal Navy, and at the age of thirteen and a half years followed his father into the Navy as a Naval Cadet. In HMS Britannia (then the Royal Naval College, Dartmouth) for the next three and a half years Derek was given a very broad – for those, even more for present times – education, for it was in the sciences and the humanities, in marine engineering and in seamanship, before going to sea as a midshipman in the 16″-gun battleship HMS Rodney for some two years. He then completed his sub-lieutenant's qualifying courses in navigation, gunnery, torpedoes, anti-submarine warfare and signals in 1939, as the Second World War broke out, when he again went to sea.