'I intend to die in the harness': Chapman Pincher is still on the hunt for spooks

Charlotte Philby meets the great spy-catcher of Fleet Street.

No, we won't start with that, we'll start in India…" So begins an interview with Chapman Pincher, the great spy-catcher of Fleet Street who, nearly 50 years after being voted Journalist of the Decade, still knows how to steer an interview, even if – as I am minded to tell him on several occasions – it is me who is supposed to be interviewing him.

No sooner have we crossed the threshold of his living room, which is decorated wall-to-wall with pictures and trinkets collected over nearly a century on this planet, than Pincher is flicking through a great pile of paper and books – material he has gathered to illustrate various points he wants to make during the course of our meeting.

He's been going through things, he explains, while researching his autobiography, which he intends to call "My First 100 Years!". Unsurprisingly, there's been rather a lot to recall.

Chapman Pincher is an emblem of the Cold War who earned his colours as the science, defence and medical correspondent on the Daily Express. Over the course of a glittering six-decade career, he became almost as notorious as the spooks he relentlessly chased. During his time on the Express under Lord Beaverbrook, where he says he "pioneered a kind of investigative journalism", he made friends and enemies in high places. "I always tried to meet all the top people because that's where the stories lay. When you have access to people you have access to facts, usually secret facts…"

So influential was he that, in 1950, Prime Minister Harold Macmillan wrote, "Can nothing be done to suppress or get rid of Chapman Pincher?".

These days Pincher lives in a red-brick house at the end of a lane in a picturesque village as quintessentially English as he is. A sign on the window reads, 'Lovely woman and grumpy man live here'. The lovely woman in question is his wife of 47 years, Billee, with whom he shares (from both their previous marriages) five children, 13 grandchildren and two great-grandchildren.

Inside, there is a tray laden with shortbread and a pot of tea. Despite his friendly demeanour, Pincher has dedicated his life to exposing traitors and double agents – including my grandfather, Kim – and for a brief moment I imagine myself taking a bite and keeling over, gasping for breath as the poison takes hold, a final act of retribution. As it happens, Pincher seems content that Kim Philby and his Cambridge lot got their comeuppance on Earth. During a year-long email correspondence, Pincher once told me: "The Russians are an unpredictable lot as no doubt your grandfather found out."

More to the point, surely Pincher's been too busy to be stockpiling arsenic… Fast approaching his 99th birthday, the insatiable hack is still working seven days a week. "I won't take a day off because it's a use-it-or-lose-it situation at my age and you lose it quickly. I intend to die in the harness, like the old war-horse.

"I've got this bug, you see, of wanting to know everything there is to know about the spy world," he says in a soft Yorkshire drawl, peering over the top of his spectacles. To this end, every day after breakfast with Billee, he checks his emails before setting to work. Right now he's finishing off the second draft of his autobiography – his 38th book – alongside some "ongoing research".

The rest of his books are lined up under 'P' for Pincher in an alphabetised shelving system that covers the walls of his study. Proudly, he scans the titles – among them, nine novels including one called Life's a Bitch!, told from the perspective of his dog, a greying chocolate Labrador named Tom. Then there is the one he wrote last year, an "uncensored and updated" version of his sensational 1981 magnum opus, Their Trade is Treachery, which he co-wrote with Peter Wright ("He was a greedy sod").

Here in the study, he unveils his prize possession, a slide enlarger which belonged to a woman called Bridgette, the sister of one of Pincher's great nemeses, the British housewife who was awarded two orders of the red banner for services to the Soviet Union, codename 'Sonia'. "Sonia's sister, she was responsible for a lot more than people know," he says.

In one of the cupboards, there are 37 cuttings books, with every single article he has ever written neatly filed. Along with lines of ring-binders with labels including 'Hollis, Personal: Pre-marriage', filled with papers that his son and grandson dig out for him from the archives. "It is all there," he says, "not just in the old bonce," he adds, tapping his temples.

Treachery: Betrayals, Blunders and Cover-ups: Six Decades of Espionage is 688 meticulously-researched pages in which Pincher, who famously helped unmask the Cambridge Five, strengthens his allegation that former MI5 chief Peter Hollis was a Soviet super-spy who was at the heart of a ring of double-agents poisoning the Secret Intelligence Service from within.

As part of an ongoing mission to out Hollis before he dies, Pincher has been spending much of his time here in the study of his red-brick cottage in a picturesque pocket of West Berkshire, wading through the pre-war journal entries of Guy Liddell, another British intelligence officer, which were released into the national archive last year. A friend of his has been emailing them across page by page: "I've gone right through the whole thing and there isn't a single fact I have to change in Treachery. I thought there might have been one or two things that weren't quite right… not one!" he beams.

But he isn't done yet. "What's left is a lot of things I regard as like doing a giant jigsaw, I've got most of it done but there are gaps, little bits keep coming in and I keep filling it in."

Chapman Pincher's real name is Harry: "When I joined the Express they said, 'We like pretentious names here, what's your middle name?'. I said 'Chapman', he said 'That'll do' and I've been stuck with it ever since."

Born in Ambala, India in 1914, his first memory dates from when he was three, having just moved back to England and seeing the bombs dropping near Pontefract. From that moment on, he has almost perfect recall. It was part of his genius as a journalist that he never had to make a single note. Without having to strain, Pincher can remember almost every detail of everything that has ever happened to him, which is no small feat given the volume.

With his father in the army – "He ended up as a Major from very ordinaryf beginnings" – Pincher had attended 13 different schools before the family settled in Darlington, a market town in the north-east.

When he was 10, Pincher won a scholarship to the local grammar school before going on to study at King's College, London where, as an undergraduate, he published "two highly original papers", one on "the genetic interpretation of hysteroscopy and related conditions", and the other "a genetic interpretation of the alteration of generations". So impressed was his professor that he invited Pincher to join the staff. "I joined as a demonstrator – the lowest of the low in the academic world, but it was a start."

After a stint at the Liverpool Institute where he earned his teaching diploma, he took up his first proper post, earning £249 a year. "The pay was terrible. I thought 'you've got to do something about this'," so he started writing articles for agricultural newspapers. At lunchtime he would go to the library, look things up and then write about them. Reaching into his pile of books, Pincher pulls out a small Penguin paperback entitled The Breeding of Farm Animals. "I did all the line-drawings for all my own books," he says, flicking through his first published book, a farmer's hand-guide. "This little book would later change my life…"

When war broke out, Pincher was enlisted. He trained as a tank gunner rising to the "dizzying rank of corporal" – "I wanted to know everything, always have" – and was eventually sent on an advanced course in ammunition and explosives at the military college of science before being transferred to rocket research, where he remained until the end of the war, involved in producing rocket weapons for the RAF and the Navy.

In his twenties, Pincher lived with a friend, Arthur Christiansen, who was the editor of the Daily Express. One day his friend rang to pick his brain on RDX (Research Department Explosives) for a story they were writing, and as a result the paper got the best story. The same happened with the Doodlebug and then the V2 rocket. "I knew everything about all of them." Finally, in August 1945, the atom bomb went off over Hiroshima and nobody knew anything about it. "Beaverbrook, the owner of the Express, got on the phone to the paper and said, 'Your headline for tomorrow: The bomb that changed the world. And you've got to keep the story going for at least a fortnight'." They knew who to call. Except this time Pincher didn't have the answer.

"I knew nothing about the atomic bomb, but I did know that one of the guys who'd worked on it was at Birmingham University. I rang him and he said, 'Why don't you get hold of that report? The Americans have published a report telling the whole story…'. He said, 'There's a copy of it at the headquarters of the British Atomic Establishment. If you go there and say I sent you they might let you see it'.

"So I turned up there and they brought in this." Seated in his armchair, his wife Billee listening on from the corner of the living room, Pincher produces a bound version of the book – the Smith Report. "I sat there for seven days and I read it. I've had amazing strokes of luck all my life and one of them was this: there was I reading this report but it wasn't out in America, it had been held up for a week, so I got the world scoop every day!" Christiansen was over the moon, and Pincher's fate – taking up the position of defence correspondent at the best-selling British paper – was sealed.

"One day I was on a meetings visit with all the other defence correspondents to Farnborough. When we finished, we got on this bus that took us all to the main gate. Sitting opposite me was a little chap in a bowler hat, pinstripe suit and briefcase… I can't think why but he said to me, 'Are you Chapman Pincher?'. I said, 'Yes'. He said, 'I'm so pleased to meet you, I've just read your book, The Breeding of Farm Animals, it's taught me so much,' he said. 'My name's Fred Brundrett and I'm a civil servant but at the weekends I'm a farmer; would you like to come and see my herd of red bull cattle?'."

As it turned out, Brundrett was deputy chief – soon to be chief – scientist in the Ministry of Defence, and they became "such pals". "We lunched regularly… He became a major source of leaks to me, he treated me as though I was any other member of the Ministry of Defence, there was very little I didn't know.

"In life, it is about the people you meet," and Pincher met a few. Margaret Thatcher, among them, whom he introduced to the head of MI6 while she was still in opposition. They were great friends, too, until she became Prime Minister and got hold of an advance copy of Their Trade is Treachery, in which Pincher and Wright implicated the MI5 in all sorts of blunders and cover-ups. "From then on," he says, "all I got from her was stony stares."

He became close, too, to his boss Beaverbrook: "He was not at all like people pretend he was. He was mischievous but he wasn't… evil… I said to Enoch [Powell] once, also a great friend of mine, he has sat here in this room many times… I said, 'Would you like to meet Beaverbrook?'. He said, 'No, I like to see evil not embrace it'… but there was nothing evil about him. He was enormous fun.

"I was the first one to know that [Beaverbrook] was mortally ill…" Pincher adds. "I was salmon fishing in Scotland, I went into the bar prior to dinner… there was a fellow there drowning his sorrows in drink, a Harley Street doctor. He said, 'How's your boss?'. I said, 'Fine'. He said, 'He'll be dead in six months'. When I got back I told Lady Beaverbrook and she said 'For God's sake, don't tell the lord'. He'd already been told but it had hit him so hard that they got another doctor to say they had been wrong, that it wasn't in fact prostate cancer but lumbago."

There were high-profile altercations, as well: Pincher and his friend Harold Wilson had "a real set-to" over 'the D-Notice affair', but once the Prime Minister left politics, Pincher was invited to tea at a mutual friend's to help patch things up: "Here was this man who had been Prime Minister for all those years and he held out his hand and said, 'I'm sorry we fell out, Harry, it was all my fault'… He didn't know I was a Yorkshireman. He said, 'Aye, I wish I'd known; it would have made a difference, you know'."

Not to mention plenty of bad feeling between Pincher and the Cold War double agents who he made it his life's mission to uncover. Which makes his recent courting by Russia more than a little incongruous.

"Would you believe it?" Pincher hoots as he pulls out a final envelope. In it is a certificate stating that he has just been made a fellow of an academy set up to advise Putin. "They were looking for some foreign members and they elected me. I belong to the academy in the rank of professor!" he howls with laughter. To prove it, he has a certificate, a sash and an ID card in case he ever wants to visit – "Which I won't! Oh, it's a bloody good joke".

Strange as it may seem, it wasn't the first time the Commies have come knocking. As a student at King's College, London, he says, his fellow students tried to sign him up to the Soviet cause: "They worked on me enough to attend quite a few Communist meetings, I read the Daily Worker, I got quite interested… I said to one, 'In the event of a successful revolution how would the new England be governed?' He said, 'To start with it would be governed from Moscow,' so I said, 'Well bugger that!'."

But not so for the British intelligent services: "I asked one once, 'Why did you never approach me?'. He said, 'We thought about it but decided you'd be uncontrollable'. I said, 'You're bloody right!'."