The Office of the Judge Advocate General became a purely judicial department, responsible to the Lord Chancellor, though very much bigger than the pre- war judicial section and on terms of appointment similar to those of judges. What had been the Military and Air Force Departments responsible for prosecution were removed altogether from the control (which had, in any case, been purely nominal) of the Judge Advocate General, becoming the Legal Directorates of the Army and the RAF, responsible to the chief personnel officers of their respective services. In 1955, after several years of intense preparation, the Army and Air Force Acts - the Acts which govern the discipline and certain aspects of those services - were themselves completely rewritten.
When Barnett joined the office in 1934, its judicial department - civilian barristers who sat as judge advocates at Army and Air Force courts martial and, working directly under the Judge Advocate General himself, supervised the validity of military trials - was very small; it numbered only four or five people. While there were also Military and Air Force departments, staffed by legally qualified Army and RAF officers, who were responsible for advising on and sometimes conducting prosecutions, they were quite separate.
Barnett found the move highly congenial. The office combined the interest of the criminal law with the world of the armed forces, whose society he enjoyed. He rose rapidly in the hierarchy; having joined as Legal Assistant, by 1938 he was First Deputy. The outbreak of war in 1939 changed everything. The enormous expansion of the armed forces which followed had to be reflected in the departments of the Office of the Judge Advocate General. They were augmented by drafting in large numbers of wartime officers who had been lawyers in civilian life. Many of those chosen to join the judicial department had been eminent in their profession and some of them were, when the war was over, to attain the highest judicial offices. The pre-war civilian judicial staff were themselves commissioned into the armed forces, Barnett into the Royal Air Force. He ended the war as a Wing Commander, but with the return of peace returned to civilian status, by now an Assistant Judge Advocate General.
Barnett's experience of military law became almost unrivalled. But in the setting up of the new-style Judge Advocate General's Office, within the Lord Chancellor's establishment, he brought to bear personal qualities no less valuable. A natural urbanity of manner, tact and a gift for making friends of those with whom he was working helped him greatly in the delicate negotiations over such vital matters as remuneration and terms of service for him and his colleagues. In 1955 he was appointed Vice Judge Advocate General and in 1962 Judge Advocate General.
The first time I set eyes on Oliver Barnett was in January 1955 in a room in the House of Lords where I was waiting to be interviewed for a vacancy in the Office of the Judge Advocate General. He came in a few minutes after me, sat down across the room and disappeared behind his newspaper. Taking him for a rival candidate, I studied him closely and my heart sank. He was rather older than me, beautifully tailored and shod, and with an air about him of such calm and imperturbable self-possession that nobody in his right mind could have hesitated for a moment if called upon to choose between us. I nearly gave up there and then and slunk out, leaving the field to the only possible choice.
Fortunately, he turned out to be there as one of my interviewers. He was in fact older than I had judged him to be, one of those men who change little as they age. Well into his eighties he kept the dark smooth hair, bright eyes and ruddy complexion he must have had as a boy, the same trim figure and air of dignity and imperturbability. A contemporary who was at school with him 75 years ago recalls vividly being behind Barnett in a queue of boys lining up for caning. Barnett, calm and impassive, went in when his turn came and emerged still outwardly quite unruffled and with the same "stately" walk that his old schoolmate remembers him always possessing.
Born in 1907 and brought up the son of a First World War widow, Barnett was educated at Eton. From an early age he took an interest in crime and criminal law. As a young man of 18 he became a Special Constable (and also, for a time, an unofficial prison visitor) and in 1928 he was called to the Bar, practising at first on the Oxford Circuit and at the Old Bailey. In 1931, he joined the staff of the Director of Public Prosecutions. Three years later, however, a vacancy occurred in the Office of the Judge Advocate General for which Barnett successfully applied.
Barnett always claimed to have realised early in life that his was not an exceptional intellect and that to succeed he would have to make up for it by outstanding attention to method and detail. Everything was noted and indexed, the margins of his working textbooks filled with notations in his small but clear hand, so that the vast majority of legal questions he was called upon to consider could be answered almost instantly by reference to some previous occasion on which he had been called upon to consider it and reproduction of the clear and careful answer he had written then. It saved him, and his helpers, a great deal of time.
By nature reserved and in professional matters cautious, he had another side. He was a genial and convivial man, a member of Brooks's and of Pratt's, who enjoyed the company of friends. Nor were his views always consistent or predictable. In 1967, when the objective blood alcohol level test was first introduced to replace the old subjective judgement of policemen or police surgeons, which often led to very protracted trials, a member of his staff, knowing how much he valued precision in legal matters, remarked to him that as a lawyer he must welcome this simplification.
Barnett's reaction was instant, unexpected and vehement. He abominated the innovation. It meant that country gentlemen like himself, well aware of their own capacity for drink and completely confident of their ability to drive home from dinner parties responsibly and safely, were now at risk from any officious prowling country policeman.
He was appointed deputy chairman of Somerset Quarter Sessions in 1967 and continued to sit until 1971. His principal recreation in his retirement was his keen interest in horse racing.
Oliver Charles Barnett, lawyer: born 7 February 1907; called to the Bar, Middle Temple 1928, Bencher 1964; Legal Assistant, Director of Public Prosecutions 1931-34; Legal Assistant, Judge Advocate General's Office 1934-37, Second Deputy Judge Advocate 1937-38, First Deputy Judge Advocate 1938-39, Assistant Judge Advocate General (Army and RAF) 1947-54, Deputy Judge Advocate General (Army and RAF), Germany 1953-54, Vice Judge Advocate General 1955-62, Judge Advocate General 1963-68; OBE 1946, CBE 1954; QC 1956; Kt 1968; married 1945 Joan Eve; died 3 February 1995.