A few weeks ago, Paul Asprey, a Falklands veteran from Darlington, celebrated his 50th birthday. Nobody was more surprised than he was to have survived that long. The former Navy signaller was caught in a fireball on board HMS Hermes when a Harrier jump-jet exploded on take-off. Since then he has suffered from post-traumatic stress disorder (PTSD), has twice tried to take his own life, been sectioned under the Mental Health Act and drunk himself into oblivion more times than he or anyone else close to him cares to remember.

“It got to the stage I was living in a one-bedroom flat, where I locked myself in and wouldn’t answer the door or the phone,” he said. “It was like being in a prison cell. It was not living, and it was very difficult to carry on.”

Today Mr Asprey, whose family abandoned him, has remarried, and is looking forward to resuming a relationship with his grandchildren, the youngest of whom he has seen only twice in her two-year-old life.

He is one of the success stories of Combat Stress, the charity formed after the First World War to help former Armed Forces personnel suffering from service-related mental health problems. This weekend, while the country is paying tribute to those who have fallen, the organisation will mark its 90th anniversary. Since the charity was founded, however, the services it provides have changed significantly in order to respond to the changing profile and needs of mentally ill veterans.

In recent years, the age of veterans seeking help from Combat Stress, which runs three respite centres throughout Britain, including Hollybush House, in Ayrshire, has dropped dramatically. In 2000, the charity did not treat anybody aged 20 or younger. Figures reveal that currently, they are treating six, some of whom are still in their teens, while the number being treated aged between 21 and 30 has also risen to 225, from 160 in 2000. At the other end of the scale, the number aged between 71 and 80 has reduced by four fifths, dropping from 1,000 nine years ago, to 207.

Despite the decline in older veterans as they pass away, the total number being treated by Combat Stress has risen by about 11 per cent in the past nine years. The increase is due mostly to a jump in referrals from Mr Asprey’s age group, aged 41 to 50.

The number of men and women in this category — mostly veterans of the Falklands conflict and Northern Ireland — being cared for by Combat Stress has doubled in the past nine years, rising to 1,261 from 620 in 2000.

Among Falklands veterans it takes 14.3 years on average for PTSD to emerge, meaning that many have only recently had it diagnosed and entered the system. Among veterans from more recent wars a different pattern emerges. To date, 129 former service personnel from Afghanistan have contacted Combat Stress for help. The average time between discharge and approaching the charity is just 17.6 months, and the average age is 32. Among the 589 Iraq veterans who have been referred to Combat Stress, the average time between discharge and seeking treatment is 19.3 months, while their average age is 33.

Clive Fairweather, chief fundraiser for Combat Stress in Scotland, and a former commanding officer of the King’s Own Scottish Borderers, believes that the time difference in reporting symptoms is due to PTSD becoming more acceptable to society.

“Over the period of 90 years, since the charity was established, there have been two main changes: the first is the nature of war, and the fact that it is very much on television,” he said. “The public is far more informed than previously through the media. The second thing is the way mental health problems are viewed by the Army and society in general. In the Great War, you could be shot for cowardice, or committed under military law to Craiglockhart Hospital. You got very little sympathy from anybody.

“Now the Army is more attuned to mental health casualties, and the public has more sympathy,” he said.

“It is a big sea change and just in time because there is going to be a lot of casualties in the years to come following Iraq and Afghanistan.”

PTSD is associated with a number of different symptoms but the most common include depression, heightened anxiety, phobias and drink and drug addictions. Treatment for sufferers includes cognitive behaviour therapy and psychiatric support.

Mr Fairweather says that the problems suffered by Falklands veterans, such as Mr Asprey, could be a portent. “It was the last major war involving Britain before Iraq and Afghanistan,” he said. “It is a warning. Two hundred and fifty five died in the Falklands, and more than 300 are thought to have taken their own lives since serving there. On Remembrance Day we remember the fallen, but there are many more out there with PTSD who are the living dead that we need to get to. The quicker we can get them the less likely they are to be involved in alcohol or drugs, which make it far more difficult to give effective treatment.”

Mr Asprey, who was an alcoholic, was diagnosed with PTSD in 1993, 11 years after he had served on board the aircraft carrier HMS Hermes. Looking back, Mr Asprey thinks that the four-month posting was the beginning of a lifetime of fear. “You never got any sleep — you only laid on top of your bunk. I still only get about four hours of sleep at night.

“I also remember I didn’t like going for a shower, because it was below the water line, even though it was probably the safest place to be in a fireball.”

Mr Asprey stayed in the Navy for another five years following the Falklands, but did not want to go back to sea. After being discharged he joined the police — he thinks he was trying to prove to himself that he was not a coward — but lost his job for reporting for duty drunk. At that time, he thought alcohol would help him to relax. “I could be walking down the road and I would start smelling salt,” he said, “or hear a noise like waves lapping against a ship. Every time I see an aeroplane I am waiting for it to blow up because of that Harrier.”

His journey to recovery since diagnosis has been slow, but steady. He has gone from regarding those who lost their lives during the Falklands campaign as “the lucky ones”, to enjoying a new relationship with his children and grandchildren, who now forgive him for turning to drink. “At one time they did not want anything to do with me,” he said.

Although his treatment is aimed at helping him to forget his ordeal, he says his greatest wish is to relive the moment he thought he might lose his life: “If somebody said to me you can have half an hour, I’d go back and do it all again because I know I’d get out at the other end,” he said.

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