Chapman Pincher, who has died aged 100, was a writer and investigative reporter famous for a succession of scoops during the Cold War and was frequently a thorn in the side of Government - so much so that, in 1959, the Prime Minister Harold Macmillan wrote a memo to his Defence Minister asking: "Can nothing be done to suppress or even get rid of Mr Chapman Pincher?" Pincher often wondered exactly what the Prime Minister meant by "get rid of".
At the height of his career, so much classified information was coming Pincher's way that the historian EP Thompson once referred to the journalist as "a public urinal where ministers and officials queued up to leak", although some critics accused Pincher of allowing himself to be used by Government.
Pincher himself maintained he was always willing to attack whoever was in Government, right or left, and said that one of the motivations which drove him on was the continuing attempts by Governments of all kinds to cover up their mistakes.
In all, he spent more than 70 years as an investigative writer.
He was born Henry Chapman Pincher in Ambala, India, where his father Richard was serving with the Northumberland Fusiliers; his mother Helen was with her husband because he expected to be stationed in the country for two years.
Shortly after the outbreak of the First World War in August the same year, Major Pincher was recalled to the UK and in the years that followed the family moved from one posting to another, with young Harry, as he was known, attending 13 different schools.
After the war, the family lived in North Yorkshire, where Pincher's father ran a pub.
As a child, Pincher was deeply interested in natural history and had ambitions to become a botanist. He studied the subject at King's College London and in the 1930s became a biology teacher at a boys school in Liverpool.
However, he was also interested in writing and his first experience was freelance articles on agriculture and veterinary subjects for scientific magazines. Soon, he was earning more from his writing than his teaching.
His career was then interrupted by the Second World War, during which he was sent for training all over Scotland with the Sixth Armoured Division to prepare for landing operations in France. Towards the end of the war, he was involved in the testing of assault rockets to be used in the D-Day landings.
It was his work on rockets that led to his start in journalism. He bumped into an old friend in London one day who told him he was working in Fleet Street for the Daily Express. When the friend heard about Pincher's experience with rockets, he asked for his help on a number of stories. This then led to Pincher being offered some experience working in the Express office as a writer.
It was while he was still in this junior position at the Express that he was involved in his first scoops. After the atomic bomb was dropped on Hiroshima at the end of the Second World War, the paper was desperate for stories on the subject and any news on British plans for nuclear weapons. Pincher discovered a US government report had just been released and managed to see an advance copy. The succession of stories that followed led to Pincher being offered the post of defence and scientific reporter on the Express.
In the years that followed, he was responsible for many important stories, usually on defence, security and surveillance matters. His technique was almost always the same: he would befriend senior Government figures, take them to lunch and make sure they had plenty to drink.
He would never drink himself and would never take notes either because he thought the sight of a notebook could inhibit his interviewee; instead, he committed the whole lot to memory and wrote it down as soon as he got back to the office.
The technique worked again and again and one of his biggest stories in the 1960s was the revelation that all private cables and telegrams sent from Post Offices were made available for scrutiny by the security services - a story that caused one of many confrontations between Pincher and the Government of Harold Wilson. At one point, Wilson became convinced MI5 was deliberately leaking information to Pincher to undermine him.
In the early 1980s, Pincher also worked with the renegade MI5 officer Peter Wright on a book Their Trade Is Treachery, which related the extent of Soviet penetration of MI5. Its most staggering revelation was that the director general of MI5 himself, Sir Roger Hollis, had been suspected of being a Russian agent while in charge between 1956 and 1965.
The Prime Minister Margaret Thatcher was then forced to admit in Parliament that Sir Roger had been interrogated on the matter. Pincher's book with Wright later formed the basis of Spycatcher, which Mrs Thatcher's Government tried to ban.
Pincher also often wrote on health matters and in 1954 went to his editor with a story about one of the first medical studies showing that regular cigarette smoking causes lung cancer. His editors, in the typical smoke-filled newsroom of the time, decided the story was unlikely and refused to use it. A non-smoker for most of his life, Pincher was proud the story was, in the end, proved to be true.
After a long career with the Express, Pincher eventually retired from the newspaper in 1979, exasperated at what he saw as an obsession with trivial journalism at the expense of serious news.
He continued to write extensively though, working on books, freelance articles and a number of novels. His memoirs Dangerous To Know were published this year when he was 100.
Announcing his death after suffering a stroke seven weeks ago, Pincher's son Michael said his father had faced the end of his life with no regrets or fear and even a joke: "Tell them I'm out of scoops," he said. He is survived by wife Billee, their children Pat and Michael, and their grandchildren.