Ian Mather will remember forever the words of an Argentine naval officer uttered to him in an airport lounge in Buenos Aires in 1982: “for you the war is over.”

This pronouncement marked the beginning of a three-month incarceration in an Argentine cell for Mather and two of his journalistic colleagues, suspected of being military spies during the Falklands War.

Mather had eagerly gone to Argentina at the beginning of the conflict as The Observer’s defence correspondent – only to be caught up in a misunderstanding which saw him imprisoned for the duration of the war.

Now the journalist, who began his 48-year career at the Press Association, has decided to tell his story in a self-published book – its title taken from those enduring words: For You The War Is Over.

Sat in his Muswell Hill living room, where he has been based for 30 years, Mather takes a very journalistic view of the event.

“I wanted the book to be realistic. It is a non-fiction work, it isn’t dramatised in any way. A lot of my peers believe that I was too realistic, though. Some people have said that I should have made it more dramatic. They are, of course, concerned with the altruistic side of journalism: that there is a journalistic mission to document and explain events. I didn’t want to be a martyr.”

This practicality comes with experience. Even at the time, Mather’s Falklands mission was not out of the ordinary for him. As a war correspondent, he had already reported from the Vietnam War, the Nigerian Civil War and covered the Soviet invasion of Czechoslovakia.

“I’d been to quite a lot of wars and seen riots and revolution before,” says Mather, now 75. “The difference was they had not involved Britain.

“This was the first time I’d actually been reporting a war where Britain was directly involved and I went about reporting it in exactly the same way – talking to diplomats and military officials, which was in hindsight a mistake.

“When we were arrested, they saw the information I’d collected, from military officials, as exactly the kind of information I shouldn’t have. I perhaps should have realised that I had to be a little more careful.”

Faced with an ardent group of Argentine military officials, Mather was somewhat unexpectedly delighted. “My first thought was, ‘This is a great story.’ I didn’t actually have a good story for that week’s paper. I thought I would join the ranks of journalists who had been locked up trying to do their job. At that time, I believed we would be rescued in a couple of days.”

Mather soon realised his estimate was optimistic. “The worst part was when I realised we were not going to be immediately released. I felt then we were in danger because this was the time of death squads.

“At that time, you communicated through cables, and communication wasn’t constant. So The Observer didn’t immediately realise I was missing when I didn’t file.” Even when an alarm was raised by The Sunday Times, it took 77 days – the duration of the war – to have the three journalists released.

Mather was sent to Ushuaia prison at the southerly tip of Argentina, blasted by the harsh Antarctic climate.

He was kept in an 8ft by 6ft cell with the other journalists. His diet included chicken necks and the shower consisted of a tuna can with a hole. “I did develop relationships with the guards and other prisoners,” he says. “I didn’t know what crimes they had committed, but they were decent human beings. In a way, I would have liked to have stayed in contact with them.

“It did give me an understanding and a soft spot for prisoners, having been one for three months. There’s just something so pointless about being sat around all day doing nothing. Some of them would just sit there and stare at the floor all day.”

Mather’s overall reflections are humbling.

“It wasn’t a life-changing experience,” he insists. “My father served in the war and when he came back he never wanted to leave home again. For me it wasn’t like that; it never made me want to give up my job.

“The most memorable thing I recall about my time as a foreign defence correspondent was generally the extraordinary circumstances you were always in and the people you met, rather than any specific event. It was only when I stopped I realised how bizarre my job really was.”

o For You The War Is Over is available via Amazon at �7.50 or at ianmather.co.uk.