Sir Gordon Downey, who has died aged 93, leaves a substantial legacy of parliamentary and government scrutiny. In the 1980s this quiet civil servant created the modern National Audit Office (NAO), and in the following decade investigated major political scandals as parliamentary standards commissioner, among them the “cash for questions” affair, initiated by the Guardian. In this, he found “compelling evidence” that the MP Neil Hamilton accepted cash for lobbying from the former Harrods owner Mohamed Al Fayed. The matter came to light when Fayed told the editor of the Guardian, Peter Preston, in an aside that he had to pay two Conservative MPs, then junior ministers, Hamilton and Tim Smith, money to ask questions in parliament over a long-running dispute between Fayed and Tiny Rowland, a British businessman, over the ownership of Harrods. He also cited Ian Greer, a former Tory agent who ran one of the biggest parliamentary lobbying companies at the time, as the conduit for the arrangement. When the story broke in 1994, both ministers resigned. Smith admitted accepting money but Hamilton and Greer denied it and sued the Guardian. In 1995 the Tory prime minister, John Major, set up the committee on standards in public life, chaired by Lord (Michael) Nolan, laying down seven principles as a code of conduct for public life. The Nolan committee recommended the appointment of a parliamentary commissioner, the post that Downey took up. Hamilton and Greer’s case collapsed in 1996. Greer’s lobbying company went bust and he left the country for South Africa. Hamilton subsequently lost his safe Tory seat in Tatton to an independent “anti-sleaze” candidate, Martin Bell. Following a long and complex investigation, in which Hamilton kept denying the allegations and tried to blame journalists and Fayed for the scandal, Downey said the evidence that clinched the case – about the handing over of up to £25,000 cash in brown envelopes – came from one of Fayed’s former staff, who was studying to be a lawyer. She would, he reasoned, have risked ruining a promising career if she had lied to him. However, Downey’s report came after the 1997 general election. Since Hamilton had not been returned to the Commons, there was no scope for its standards and privileges committee to suspend him, and it could go no further than allowing Downey’s conclusions to stand. Dale (later Lord) Campbell-Savours, then a Labour MP, who saw Downey regularly as auditor general and parliamentary commissioner, described him as having “an agile brain, very forensic”. Downey had a meticulous grasp of detail and was a consummate Whitehall player. Born in Wandsworth, south-west London, the son of Winifred (nee Dick) and Stanley, an accounts manager, Downey was educated at the Tiffin school, a boys’ grammar school in Kingston upon Thames. His father died in the second world war, leaving his mother to bring up Gordon and his two older sisters. Following national service with the Royal Artillery he took an economics degree at the London School of Economics and in 1951 started his first job in Whitehall at the Ministry of Works. A year later he moved on to the Treasury. He served as assistant secretary to successive chancellors, including Rab Butler, Peter Thorneycroft and Harold Macmillan. Downey soon rose to become deputy secretary at the Treasury before in 1978 being loaned as deputy head of the central policy review staff, where he ended his Whitehall career in 1981. He then became comptroller and auditor general, at that time part of the exchequer and audit department, run by the Treasury. His predecessor, Douglas Henley, had wanted to turn it into an independent body. It was left to Downey to undertake the task. The Treasury had run the department since the days of Gladstone and was firmly opposed, and the government did not allocate time to change the law. But Norman St John-Stevas, a former cabinet minister who had been sacked by the prime minister, Margaret Thatcher, as leader of the House in 1981, promoted the change in a private member’s bill in 1983. When Thatcher called a general election, the bill became law without further debate in what is known in parliament as the “wash up” of partly completed legislation. The change wrong-footed the Treasury and also the security services, which found their spending for the first time examined by an independent body, the NAO, and the following year Downey was knighted. He used the NAO’s new independence to change its profile. It produced the first value-for-money reports on government departments, which would then be published and later scrutinised at meetings of the House of Commons public accounts committee. This process became a powerful tool for politicians and the public for scrutinising the workings of government. It has exposed waste and scandals across Whitehall. Downey ran into trouble in 1987 when the New Statesman investigative journalist Duncan Campbell accused him of hiding from parliament plans by the Ministry of Defence to build a top secret military satellite called Zircon. The row escalated when Special Branch raided the magazine and the BBC’s then director general, Alasdair Milne, decided not to broadcast a documentary on Zircon that had been commissioned by the BBC from Campbell. In the melee that followed, Milne resigned, but Downey survived, issuing a rare four-page press statement denying he had covered Zircon up. He did not deny the plan existed but said it did not reach the level of expenditure required for publication to parliament. The satellite was never built. Downey left the NAO in 1987. As complaints commissioner at the securities association (1989-90), overseeing stockbrockers, he investigated the procedures used to handle complaints. Further city regulatory posts followed with Fimbra, responsible for independent financial advisers (1990-93) and the PIA (Personal Investment Authority, 1993). In parallel he became readers’ representative at the Independent newspaper (1990-95), investigating complaints about articles, and then came the parliamentary commissioner post. Downey found shortcomings in the way the job had been set up. Rather than having the authority to send for all the documents in investigations, or summon people to attend, he had to get agreement with a committee of MPs to do so. In 1998 his term came to an end, and he left the job. In subsequent articles in the Guardian in 2001 Downey warned that parliament risked losing public confidence in scrutiny of MPs. Writing about the plight of his successor, Elizabeth Filkin, when she faced problems obtaining information from Keith Vaz, on alleged undeclared outside payments, he said: “MPs need to watch their system of self-regulation rather carefully if public trust is not to be forfeited”, adding: “It is not sufficient that parliament and its officials should be at ease with themselves. It is vital that the public, too, should have confidence in the process.” Since then, parliament has altered the composition of the committee – which now has an equal number of MPs and independent appointees and it has strengthened the code of conduct so MPs have to co-operate with any inquiry by the commissioner. In 1952 Downey married Jacqueline Goldsmith, a teacher. She, their daughters, Alison and Erica, and granddaughters, Sophie and Emily, survive him. • Gordon Stanley Downey, civil servant, born 26 April 1928; died 12 April 2022