Born in Glasgow in 1952, Campbell was brought up and educated in Dundee. His mother was a mathematician who worked at Bletchley Park under Alan Turing. As a pupil at the High School of Dundee, an independent school, he first trained in computer programming aged 16, taught computer languages, and undertook programming in scientific computers languages. He gained three ‘S’ levels (the old Scottish equivalent to ‘A’ levels) in physics, chemistry, and maths, and then an open scholarship to Brasenose College, Oxford, graduating in 1973 with a First Class Honours degree in physics. The following year, Campbell completed a one-year MSc in Operational Research at the University of Sussex; the course included psychology, economics, accountancy, and model building. He later told The Independent: "It was extremely useful. It was not difficult to make the grades, though they'll hate me for saying so".
After leaving Sussex University, Campbell became a journalist on Brighton Voice. Founded in March 1973 by Roy Carr-Hill and George Wilson, the paper's content followed broadly anarcho-socialist principles, focusing on housing, the police, gay rights, civil liberties, the environment, unemployment, anti-racism, fascism, and women's rights.
He was also a regular contributor to New Scientist and Time Out magazines, which during the early 1970s had a much more radical editorial remit. In 1976, Campbell wrote a seminal story for Time Out, co-authored with Mark Hosenball, called "The Eavesdroppers". It was the first time the British news media printed the acronym GCHQ, which stood for Government Communications Headquarters, a highly secretive arm of the British secret services, responsible for communications interception.
The article led to the forcible deportation of its American co-author, Hosenball. Campbell, who could not be deported, was instead placed under MI5 surveillance, which included the tapping of his phones. The following year, Campbell agreed to talk with ex-signals intelligence operator, John Berry, at Berry's home. He was accompanied by fellow Time Out reporter, Crispin Aubrey. After a three-hour conversation, Special Branch arrested the three under the Official Secrets Act 1911, in what became known as the ABC trial.
In 1982, Campbell published War Plan UK — the Truth about Civil Defence in Britain, which revealed and discussed — often for the first time — the inadequacy and futility of the British government's preparations in the event of nuclear war.
In 1980, his article revealing the existence of the secret Standing Committee on Pressure Groups (SCOPG) in Hong Kong led to the revelation that most pressure groups and individual members of the Opposition were under surveillance by the colonial government. Duncan's article asserts that Hong Kong under then governor Sir Murray MacLehose had become a dictatorship. In his words: "Hong Kong is a dictatorship; and scarcely a benevolent one."
The Secret Society series caused a political furore, known as the Zircon affair, in 1987. The production team behind the series was threatened with prosecution under the Official Secrets Act. Campbell's front door was kicked down and his home searched, and Strathclyde Police raided the corporation's Scottish headquarters in Glasgow and seized the tapes from the offices of BBC Scotland, where the series had been made. The tapes were later returned and the series broadcast on the BBC except for episode one. The BBC decided that the first episode, about secret cabinet committees, was too sensitive to show before the 1987 general election. The Thatcher government leaned on the BBC to prevent its damaging allegations from being made public.
- The Secret Constitution: Secret Cabinet Committees - about small, secret and influential Cabinet committees.
- In Time Of Crisis: Government Emergency Powers - Since 1982, governments in every other NATO country have been preparing for the eventuality of war. In Britain, these preparations are kept secret. So what will happen when the balloon goes up?
- A Gap In Our Defences - Bungling defence manufacturers and incompetent military planners have botched every new radar system that Britain has installed since World War Two. Why? And can we stop it happening again?
- We're All Data Now: Secret Data Banks - The Data Protection Act is supposed to protect us from abuse, but it's already out of date and full of loopholes. So what kind of abuses should we worry about?
- The Association of Chief Police Officers (ACPO) - ACPO Making up their own law and policy. About the Association of Chief Police Officers and how Government policy and actions are determined in the fields of law and order.
- Communications Zircon - About GCHQ with particular reference to a secret £500 million satellite. Reference to Zircon spy satellites which the public accounts committee were not told about.
Campbell revealed in 1988, in an article titled "Somebody's listening" and published in New Statesman, the existence of the ECHELON surveillance program.
In 1999, he wrote a report on communications intelligence entitled Interception Capabilities 2000 for the European Parliament.
In 2005 and 2007, Campbell investigated and wrote criticisms of the Operation Ore child pornography prosecutions in the UK, which exposed police errors. Additionally, he "revealed how computer evidence used against 7,272 people in the UK accused of being paedophiles had been founded on falsehoods." These articles, "Operation Ore Exposed" and "Sex, Lies and the Missing Videotape", were both published in PC Pro magazine.
The Who's Pete Townshend and Massive Attack's Robert Del Naja were both cleared of charges they accessed child abuse images through the Landslide site by the investigation detailed by Campbell in PC Pro magazine. When their credit card charges and IP addresses were traced, both men were found to have accessed sites which had nothing to do with child abuse images.
Campbell is gay, and came out in 1987, and has investigated LGBT issues, including "bogus Aids and HIV medicines, quack doctors"1989 – Magazine Publishing Awards: Best Business Feature
1987 – What The Papers Say: Investigative Journalist of the Year
1987 – Freedom of Information Campaign: Media Award
1983 – Periodical Publishers Association: Specialist Writer of the Year (for reports on nuclear weapons and the Prime spy case).
1980 – Cobden Trust Award (for series of New Statesman articles on civil liberties, including an exposé on the Britain's secret telephone tapping centre)
Founder member, International Consortium of Investigative Journalists
Nominated as Rector of Aberdeen University, 1981
Consultant on telecommunications, Technology Faculty, Open University, 1976–82
Member, Labour Party National Executive Committee Study Group on Defence, 1980–1983
Member, Labour Party National Executive Committee Study Group on Security Services, 1979–83
Chairman and director, Statesman and Nation Publishing Company Ltd (publishers of New Statesman) 1990-94
Senior Research Fellow, Electronic Privacy Information Center, Washington, D.C., 1999–2000
Fellow of the Royal Society of Arts
Visiting fellow of the Media School Bournemouth University, 2002–present.