Douglas Osmond was born at 40 Stewart Road, Bournemouth, on 27 June 1914, the son of Ernest Herbert Osmond (d. 1914), blacksmith, and his wife, Eliza, née Mitchell, schoolteacher. His father joined the Royal Navy and was killed in action in October 1914, leaving Osmond and his brother William to be brought up by their mother and educated locally. In 1932 he was awarded a scholarship from the Kitchener Memorial Fund (to help the children of members of the armed services) to read mathematics at University College, London. In 1935, after graduating, he joined the Metropolitan Police under the new fast-track promotion scheme recently introduced by Lord Trenchard, Metropolitan Police commissioner and former head of the Royal Air Force. He was one of only a few university-educated recruits to have entered the police service as a constable. The Trenchard scheme, as it was colloquially known, symbolized the contemporary shift in organizational thinking from a command to a managerial approach: the scheme was designed to improve the quality of Metropolitan Police management by identifying potential managers early in their careers and promoting them directly into the middle ranks at the level of inspector. From there onwards they would rise through the ranks on their own merits. After graduating from the Metropolitan Police College at Hendon Osmond quickly became inspector. On 23 July 1938 he married Doris Evelyn (Eve) Finnemore (d. 1995), daughter of Walter Finnemore, manufacturer, at the parish church in Northchurch, Hertfordshire. They had two daughters, Nicola and Joanna.
Osmond joined the Royal Navy in 1943 and from 1944 to 1945 was seconded to the Allied Control Commission for Germany. As deputy assistant inspector-general in the public safety division he worked on plans for the post-war reorganization of the German police. After military service he returned to the police and in 1946 was appointed as the chief constable of Shropshire. He was not the youngest chief constable: Richard Dawnay Lemon was twenty-seven when made chief constable of the East Riding in 1939, and Eric St Johnston was twenty-nine when made chief constable of Oxfordshire in 1940. He was, however, one of a cohort of young Trenchard scheme graduates who left the Metropolitan Police to take command of provincial (mainly county) police forces. The reason for this drift was local pragmatism. Prior to the 1939 wartime regulations giving the home secretary the final approval over chief officer appointments, the provincial police authorities had successfully resisted the Home Office regulation that all chief constables must have prior police experience, preferring instead to maintain their long-standing tradition of appointing chief constables with social standing and military rather than police experience. Following the change in practice the graduates of the Metropolitan Police College conveniently provided county and large city police authorities with a pool of chief officers whom they deemed both professionally and socially suitable to command their police forces. Consequently Osmond and his youthful cohort formed a select group of modern career chief officers who came to dominate the police service until the late 1970s and shape its structure.
During his sixteen years as chief constable of Shropshire Osmond sought to improve the conditions of his police officers and also their efficiency. Not only did he campaign for better housing and conditions, but he also took an innovative approach to crime prevention by introducing a poster campaign that used cartoon characters and comic verse. He left Shropshire in 1962, to head the larger Hampshire and Isle of Wight constabulary, and presided over its amalgamation with the Portsmouth and Southampton city forces in 1967. He remained as chief constable of Hampshire until his retirement in 1977. Always forward thinking, he oversaw the building of new police headquarters at Winchester and campaigned for more police officers. He also took the innovative step of introducing crime prevention officers into each division at a time when policing was almost wholly reactive. During his time as chief constable he also had to manage some major local events, which included policing the Isle of Wight pop festivals (which he attended) and also the aftermath of the 1972 IRA bombing of the Aldershot barracks.
Osmond’s contribution to policing was not confined to Hampshire. Between 1967 and 1969 he served as president of the Association of Chief Police Officers of England and Wales. In the late 1960s he and the Metropolitan Police deputy commissioner, Robert Mark, reviewed the policing of Northern Ireland. Their highly critical report almost led the home secretary, James Callaghan, to replace the senior management of the Royal Ulster Constabulary, although the eventual action was the installation of an advisory committee. After retirement Osmond joined the Phillips commission (the royal commission on criminal procedure), whose report led to the Police and Criminal Evidence Act 1984.
Osmond was awarded the Queen’s Police Medal in 1962. He was appointed OBE in 1958 and CBE in 1968. In 1971 he became an officer of the order of St John of Jerusalem and was knighted in the same year. In 1981 he became deputy lieutenant of Hampshire. Having lived latterly in Shaftesbury, Dorset, he died at Sutton Veny House nursing home, Sutton Veny, near Warminster, Wiltshire, of cerebrovascular disease, on 20 April 2006. He was survived by his two daughters.