ART is always very personal, both to the artist and the viewer, so to look at some of John McDermott's paintings makes for a slightly uneasy feeling of intrusion into his mind, as his work is about his experiences in — and after — conflict.

John studied art in Glasgow before joining the Royal Navy, where he was to spend the next 27 years before settling in Exeter. He has seen conflict from two angles — mainly from being on active duty in conflicts around the world, including the Falklands, the Gulf and Bosnia, but also as a "man in the middle" as a UN observer in Cambodia in the wake of the killing fields.

It is apt, then, that his exhibition at Exeter Castle, as part of the Exeter Festival, is entitled Aftermath; he hopes it will raise awareness of the terrible problem of Post-Traumatic Stress Disorder (PTSD) among servicemen and women.

John, himself a PTSD sufferer, is passionate about getting the message across to the public that there are servicemen who have been in conflict non-stop for ten years, from the first invasion of Afghanistan, and the difficulties many of them will subsequently face in assimilating back into civilian life. "This is twice as long as the Second World War lasted," he says.

"One of the big issues we have with war-related trauma is the stigma surrounding it. We are getting better at understanding mental health, but our people are going through life-changing situations almost daily.

"Some will be quite profound and they will be bringing these experiences back home with them.

"And it's the care of our servicemen when they get home — what provision there is for them, who they can turn to to help them through some of the experiences they have had and get them back into what we would loosely call normal society? — that is important.

"No matter what you think about conflict, they are out there acting on our behalf through the will of our elected government, so we have a moral responsibility to make sure they are looked after.

"We hear of our physically injured troops getting looked after with first-class medical services, but if someone is so profoundly affected mentally eventually that they are classed as unfit for duty, they will be downgraded medically — and that means unfit for deployment and then also the job they are employed for.

"The military will look after them while they are in service, but they are not going to get a diagnosis of post-traumatic stress disorder, they will be deemed to be suffering from an 'adjustment disorder'. They may get some treatment, but it is like putting a plaster on a festering wound.

"A lot of servicemen are medically discharged from the military and go back to Civvy Street relying on the NHS, which has a low awareness of the military side of PTSD, and they can wait up to 18 months just for a consultation."

John is quick to praise the work of organisations like the Royal British Legion, Combat Stress and Help for Heroes and the generosity of the public's charitable donations, but questions what the Ministry of Defence is doing about it.

"I don't think they have a very enlightened view of it at all — they have a very defensive view," he said. "I hate to be cynical, but I think they are defending themselves against future liability."

John also expresses surprise about the number of servicemen behind bars. A recent head count done by the Veterans In Prison (VIP) organisation in conjunction with the probation officers' union arrived at a figure of 8,500 — around 10 per cent of the current prison population in England and Wales.

"It doesn't stop there," he says. "Another 12,000 are within the criminal justice system and that represents the largest professional background in prison. A lot are imprisoned for violence, predictably, drug abuse, alcohol abuse — all classic symptoms of someone going through trauma."

Since John has started advertising his exhibition, he says it has taken on a life of its own and is raising the debate to a higher level than he expected.

"But it is not about compensation, it is about care. What we have to get across — and it may sound perverse — is that these profound trauma experiences suffered are a natural reaction to something that is very unnatural," he says emphatically.

He believes that it would lift some of the stigma if the invisible wounds were treated the same as physical wounds.

"I had a friend I met at Combat Stress last year and I was shocked when he told me that he wished he had lost both his legs rather than go through what he was going through, because he said then he would be better treated and looked after," John says quietly, reflecting, too on the numbers who also subsequently suffer marriage breakdown, alcoholism, drug abuse and homelessness.

While the exhibition is aimed at highlighting these issues, John is keen that people don't think it is unremittingly grim, as he also wants to celebrate the human spirit.