As one of the country’s top forensic pathologists, he has investigated more than 23,000 deaths, including those of Princess Diana, Stephen Lawrence and the victims of many atrocities – including 9/11, the Bali bombings and the Hungerford Massacre. Any one of these would give most people sleepless nights. So now he’s retired, no one would blame Dr Richard Shepherd for putting that work to the back of his mind and moving on.

But such is our fascination with death and forensic medicine that he is in just as much demand as he ever was, albeit without his scalpel.

After the success of his memoir, Unnatural Causes, he is now embarking on a nationwide theatre tour talking about the cases and bodies that have shaped his career. And he’s just published a second book, The Seven Ages of Death, sharing more fascinating tales from his 40 years as a reallife “SilentWitness” sleuth.

“People are always fascinated by death,” he says frankly. “Death used to be part of life. In my parents’ day, death was part of everyday experience. Now, because it’s less common, people are more interested. At the same time they seldom talk about death. People now talk about passing. It’s moving the phraseology away from what it actually is and hiding it. They say, ‘He’s passed’. Well no, he’s died. I’ve spent a career in this, so perhaps I’m a little harder.”

But that matter-of-fact approach, that comes from an everyday familiarity with human mortality, belies the price Richard has paid for his demanding work. Despite previously explaining that he was “better at managing strong emotion than experiencing it”, in his own admission “cutting up 23,000 dead bodies is not normal”.

In 2016 he was diagnosed with Post Traumatic Stress Disorder triggered by a flashback to working in Bali, after the 2002 nightclub bombings by Islamic extremists killed 202 people.

“It was very odd,” he recalls. “I was making my wife a gin and tonic and the trigger was getting ice cubes out of a plastic bag in the freezer. I reached into the bag and it took me straight back to Bali and the bombing. The facilities there were so poor the only way they could keep the bodies cool was to put bags of ice from the supermarket on top of them. Suddenly I was straight back into the heat, the smell and the stress.

“It was like someone opening a door into hell through which I fell. I couldn’t work; there was an overlap between depression and anxiety. I had a strong sense of wishing to commit suicide.”

Richard’s wife Linda, also a doctor, rushed him to a psychiatric emergency department. After a course of antidepressants and regular therapy he recovered sufficiently to return to work six months later. Yet Richard says that, as professional as he tried to be, he wouldn’t be human if the stories of death didn’t affect him.

He explains: “I used to do nine cases a day. You can’t let yourself grieve over every one – for me it’s my work and each blood spot will tell me something. But you’ve got to feel it a bit, otherwise you just become totally cold and callous.”

One case he remembers vividly was the 1987 Hungerford massacre where 27-year-old Michael Ryan shot dead 16 people, including an unarmed police officer and his own mother, before shooting himself.

Richard, now 68, says: “I was very young and my boss had gone away for the summer. I was left in charge of London and the South East. I received a phone call out of the blue asking me to go to Hungerford.

“I’d just bathed the kids, read a story and put them to bed. I went straight from being a dad at home out to Hungerford, where my first job was to look at Michael Ryan who had shot himself in a school.

“There were rumours that the SAS had been sent in to shoot him, but very quickly I was able to confirm that the gun was in his right hand, he’d shot himself in his right temple and the bullet had come out of the left side and embedded itself in the wall of the classroom. It was relatively simple, but it was very strange being in a room with a man who’d killed and injured so many.”

Richard, who retired three years ago, was also flown out to New York following the attack on the Twin Towers 20 years ago next week. He recalls: “There were lots of British people in theWorldTrade Center and it was clear bodies would be repatriated to the UK.

“I felt particularly strongly that we shouldn’t increase the trauma to the families by having a second post-mortem examination back in the UK, so I was sent out to check how they were identifying bodies.”

He said: “I remember the smell of the burning building, the noise of the emergency response vehicles, the smell of the trailers, the body parts laid out, the pristine mortuary. It was an attack on the senses.

“It was so well organised and we learnt a lot, which prepared us for the London bombings four years later. We weren’t prepared here for a disaster of that magnitude so it helped us work out what we needed. In a big disaster, it is so important to get identification right as it helps the family with their grief. Even now, they are discovering DNA fragments from 9/11. It’s so hard to call a family years later and say you’ve found another piece of their loved one but it needs to be done.”

He prided himself on his ability to switch between mortuary and home but his marriage was beginning to show signs of strain and collapsed in 2007.

His wife would ask him to “show some emotion”, and he has said: “I hadn’t realised it was so tightly screwed down. I was blocking the emotion that was bad, but was also blocking emotion that was good.” Alongside the large-scale horror of disasters such as the Clapham rail crash in 1988 and the Marchioness sinking the following year, a series of deaths in custody saw Shepherd pushing for police to receive better training in methods of restraint. And experiments with the family’s Sunday roast helped make him a knife crime specialist.

Following the death of Diana, Princess of Wales in 1997 Richard was called in as the expert pathological reviewer in the formal police investigation into her death.

He explains: “I was the pathologist to the Royal Family – it wasn’t an official title – but the coroner to the Royal Family always said if I was around he would call me. I was on holiday when Princess Diana died, so I didn’t get called. Later the police set up a formal investigation and I was called in.”

Richard first felt drawn to his calling when he was 13 years old and growing up in Watford. A friend brought a copy of a book called Simpson’s Forensic Medicine into school. Richard was instantly captivated by the process of unlocking the secrets of a dead body. “It opened up a new world to me and completely grabbed me,” he recalls. “I thought, ‘Here’s a career I never knew existed’.”

After training as a doctor at St George’s Hospital medical school he completed his postgraduate training as a forensic pathologist in 1987, immediately joining the elite forensic department at Guy’s Hospital before heading his own department at St George’s ,Tooting.

He found himself working on numerous high profile cases, including the 1992 Rachel Nickell murder, the 1988 Clapham rail crash, the 1989 Marchioness disaster, when 51 people died after the pleasure boat struck a dredger on the Thames and the 1993 murder of Stephen Lawrence.

When a body is laid out in the mortuary, Richard says it is often difficult to know whether that individual’s death will have a wider impact on society.

He explains: “No death is ‘just another’ and every death is a tragedy, but pathologically Stephen Lawrence was not complex or difficult. In south London at that time there were lots of stabbings.”

The popularity of the BBC One crime drama Silent Witness, starring Emilia Fox and following the investigations of a team of forensic pathology experts, shows just how much of a public appetite there is for this branch of medicine.

Richard’s theatre tour Unnatural Causes, named after his best-selling book, will see him telling stories of the cases that have fascinated and haunted him. Meanwhile his new book, The Seven Ages Of Death, sees him sharing autopsies that span the seven ages of human existence. Yet Richard, a father-of-two, who lives in Cheshire with his second wife Linda, insists that living a life steeped in death has not made him pessimistic. If anything it has helped him appreciate life.

“I like life,” he says simply. “I like my family, my grandchildren, I like music and reading and walking and my two dogs. I like flying aeroplanes and looking after bees. Life is to be lived and enjoyed.” 

• Dr Richard Shepherd – Unnatural Causes is at theatres around the UK from October 5. drrichardshepherd.com. Seven Ages Of Death (£20, Penguin/Michael Joseph) is out today