Sir John Bourn, who has died aged 88, was parliament’s longest serving auditor general, responsible for exposing waste, inefficiency and scandal in the corridors of power, and for shaping the National Audit Office into one of the most influential, respected and feared bodies in Whitehall. During his 20 years as comptroller and auditor general, he was responsible for the auditing of £800bn of government expenditure. In his first year in office, 1988, he uncovered a political scandal over the sale of the ailing Rover car company to BAE Systems (then British Aerospace) under the Thatcher government. In a confidential memo – leaked to the Guardian - Bourn revealed the existence of £38m (later revised to £44.4m with interest) of hidden government “sweeteners” to the defence company to persuade it to buy Rover. In the 1990s, after a dispute with the European Commission, the European court ruled that the payment had been “illegal state aid”, though BAE did not have to repay the money with interest on a technicality. Bourn also opened up the royal family’s finances to scrutiny and revealed some eye-watering spending on foreign travel. A lean, soft-spoken man with craggy features, Bourn was in charge of an office of 800 auditors, whose forensic inquiries into departmental expenditure were always followed through by the Commons public accounts committee, which often produced scathing reports. He also qualified the accounts of government departments. The Department for Social Security (now the Department for Work and Pensions), for one, was regularly caught out for errors and fraud in benefit expenditure. He was born in Hornsey, north London. His parents, Beatrice (nee Pope) and Henry Bourn, were civil servants. John was educated at Southgate grammar school in north London and at the London School of Economics, where he got a first in economics. Later he became a visiting professor there. His civil service career began in 1956 at the Air Ministry. He progressed to the Treasury and then in 1964 became private secretary to Sir Henry Hardman, the first permanent undersecretary at the new Ministry of Defence. He had a brief spell at the Civil Service College before spending 12 years, from 1972, alternating between increasingly senior positions at the Ministry of Defence and the Northern Ireland Office, where he eventually became deputy secretary. One of his stints at the Northern Ireland Office saw the collapse of the Sunningdale agreement, an attempt to solve the Troubles with the introduction of power sharing. The agreement was signed in 1973 but collapsed the following year after a general strike organised by the loyalist Ulster Workers’ Council. Bourn was in charge of prisons when the Maze breakout took place in 1983, and 38 IRA prisoners overpowered guards and escaped. Within hours, he had persuaded a senior Home Office official to bring in Sir James Hennessy, the chief inspector of prisons – whose remit did not cover the Maze – to launch an inquiry. The result was substantial change in the running of the prison. From 1985 to 1988 Bourn was deputy undersecretary in charge of defence procurement – experience that proved invaluable when he switched from poacher to gamekeeper at the National Audit Office. His extensive knowledge of MoD contracts meant he knew where bodies were buried. The MoD’s failure to control the escalating cost of equipment led to a series of brutal reports from the National Audit Office condemning the ministry’s waste and incompetence. In 1998, after a six-year battle, he won the right to investigate the finances of the royal household, including money spent by the royal family on travel and maintaining their palaces. This followed the fire at Windsor Castle in 1992, when the public accounts committee wanted to look into royal finances. Huge costs on royal travel came to light, including a bill for £252,000 for the Prince of Wales to visit the Caribbean with a party of 48 people and £40,000 for a trip to America and the Caribbean for Prince Andrew, both in 2000. Bourn also initiated reforms at the National Audit Office, including abolishing the use of confidential memorandums – except over MoD matters. He was knighted in 1991. He tried to take on the scrutiny of BBC value for money, but the corporation argued this would interfere with its editorial independence. By 2004 he had negotiated a halfway house agreement, which allowed the BBC Trust to commission value-for-money reports from the National Audit Office on its terms. Eventually, his successor, Amyas Morse, won the right to full access in 2016, following two highly critical reports from the National Audit Office, in 2013 and 2014, agreed by the BBC Trust, on huge severance pay deals for senior managers and £100m that had been wasted on a digital project. Bourn’s distinguished career ended abruptly in 2007 when Private Eye sought to use freedom of information legislation to uncover his own expenses and foreign trips. Instead he volunteered full details of his trips, to destinations from Brazil to the Bahamas, to the Guardian. Over three years he had run up bills of £365,000 on travel, often with his wife, Ardita, and £27,000 on dining in top London restaurants. He stood down from the post he had held for 20 years and from his job as independent adviser to the prime minister, Tony Blair, on ministers’ interests. Bourn always insisted, though, that he had done nothing wrong, as the National Audit Office earned fees from the countries he had visited and the travel had been approved by external auditors. The newspaper coverage prompted parliament to end the right of auditor generals to remain in post until they decided to leave: his successors can do the job for a maximum of 10 years. It means Bourn will always remain the longest serving officer. Ardita (nee Fleming), whom he married in 1959, died in 2018. Their daughter, Sherida, died later that year. Bourn is survived by his son, John, and four grandchildren, Ben, Jamie, Holly and Hammerson. • John Bryant Bourn, civil servant, born 21 February 1934; died 22 November 2022