It was summer time, 1895, and East London was hot.

Two boys, aged 12 and 13, spent their days roaming the streets, sipping ginger beer, watching cricket games, visiting the sea side, and buying ice cream for their friends.

They lived down by the docks, and their dad was working at sea. The eldest boy, Robert Coombes, had just quit his job at an iron yard. He was brighter that that, he wanted adventure. His brother, Nathanial ‘Nattie’, was along for the ride.

Everything was seemingly normal. The two boys were typically cheeky, naive, innocent. They were scheming to pawn the family’s watches and their mother’s jewels for cash, and excited to see legendary cricketer W.G. Grace score a century at Lord’s Cricket Ground nearby.

When neighbours asked, they said their mother Emily had been called away after the death of an uncle. They convinced an old sailor, John Fox, to come and stay with them – making it seem as if they were being supervised, when really they needed Fox because he was old enough to pawn their household items for money. Children weren’t allowed into pawnshops.

Everything was seemingly normal for the two boys enjoying a hot summer in East London, except for the fact their mother hadn’t been called away and there was no dead uncle.

Emily’s last letter to her husband complained that the boys were eating too much – money was tight. She was anxious, no doubt counting the days until Robert Senior arrived home with the paycheck. She’d given Nattie a beating because she’d caught him stealing food, and she was likely frustrated Robert had quit his job at the iron yard. There were signs she was emotionally volatile, but friends labelled her a kind and affectionate wife and mother.

A day after she wrote that letter, Robert slept the night next to her. He was kicking and flailing about, waiting for Nattie’s signal. Early in the morning, Nattie – in the next bedroom – coughed twice. Taking his cue, Robert got out of bed and stabbed his mother repeatedly, deep in the chest, until she died. She didn’t cry out, Robert said later, when police found her maggot-ridden body next to a knife on the bed and a truncheon on the floor.

Immediately after he killed her, Robert showed Nattie their mother’s body and they covered it with a sheet, locking the bedroom door behind them.

Ten days of summer bliss followed. The boys used the pawn money to enjoy the cricket and the ice creams and the trips to the seaside.

They had 10 joy-filled days before the smell of their mother’s decomposing body became noticeable to neighbours.

“It was the moment when the boys’ private, fantasy world was ruptured. The crime was discovered and suddenly they were criminals and their mother really was dead and they had killed her,” said Kate Summerscale author of The Wicked Boy: The Mystery of a Victorian Child Murderer – a book that follows the journey of Robert Coombes through his life.

It was also the moment Summerscale stumbled upon their story – months before she discovered Robert would eventually become an Australian war hero.

“I was looking through old newspapers and came across a story about the moment that Nattie and Robert were discovered in the house with their mother’s body and arrested,” told Mamamia. “It was so creepy and shocking that I was instantly gripped by it and wanted to know more.”

So know more she did.

Summerscale followed the press coverage of the boys' arrest and the following trial. She learnt that Emily had given Nattie a "hiding" the day before her murder when she found him stealing food - a phrase that, according to Summerscale, "could have meant anything from from a regular form of discipline to something much more emotive and terrifying".

"There was plenty there to suggest the boys were afraid of and angry at their mother. But I was very careful to not blame her for her own murder," Summerscale said.

She learned how Robert was obsessed with other killers of the time. How he loved the Penny Dreadfuls - cheap fiction books illustrated with violence and adventure. The books were a source of concern to the rest of society, as they represented the growing literacy of the working class. They were described by the media as a source of inspiration (a guilty party, even) in Robert's heinous crime.

She learnt how Robert confessed calmly to police officers and that he didn't flinch as he faced the judge. He wore his best clothes to court, and possessed an air of confidence and calmness as he faced the jury.

"The newspaper reports were much more rich and colourful than they are today." Summerscale said. "Reporters would describe what the witnesses were wearing, their mannerisms and the way they answered questions. It kept me occupied for a long time; piecing together the three months between the arrest and the end of the trial."

What was most intriguing, though, were the contradictions.

"The pleasure the boys took in those 10 days was childish. It was if they were on holiday," Summerscale said. "They were also naive in that they didn't try to run. There was no way the body wouldn't start to smell or that people wouldn't become suspicious, and yet they didn't try to escape the consequences of what they'd done."

After initially confessing that Nattie 'gave the signal', Robert soon changed his story and denied his younger brother played any part in their mother's murder. Nattie was cleared of all charges and called as a witness; John Fox was found not-guilty of any involvement; and Robert faced the courtroom on his own.

The naivety; the creation of a "childish" fantasy world; and then the brave acceptance of sole responsibility was one side of 13-year-old Robert Coombes. But there was another side, also.

This was the same boy who'd butchered his mother and the premeditation involved was chilling. "Robert had any number of schemes up his sleeve for raising money and telling lies about where his mother was," Summerscale said.

"There were also moments that were extremely sinister and disturbing. Emily had groaned, for example, after Robert had shown Nattie the body. Robert then went back into the room with her alone and stayed for a while. What was he doing in there? Was he making sure she was dead? It's very frightening."

The jury found Robert guilty of his mother's murder but also declared him insane.

His father said something similar when confronted with the news as his boat docked in New York and he was rushed back to London following Emily's funeral. "My eldest boy had an abnormally developed brain," he told reporters, as depicted in The Wicked Boy. "There was always something peculiar about him."

But Summerscale doesn't believe Robert was insane. She believes the verdict was a "merciful" compromise on account of Robert's age - the jury wasn't prepared to send a 13-year-old to the gallows. Instead, he was sent to Broadmoor Psychiatric Hospital.

"It was thought to be a horror show, where madmen were sent," Summerscale said. "In reality, however, it turned out to be an extremely humane place where the staff treated the inmates as patients rather than prisoners. Robert spent his time learning and reading and eating oranges. He played music and cricket and chess. Compared to East London, it was a paradise."

The episode of Casefile you need to listen to. Post continues below.

But, as Robert was sent away, the press coverage died down and the hysteria slowly tapered. Robert was in Broadmoor till he was 30 and this is where the trail went cold for Summerscale.

"The electoral roll, the marriages and deaths records, newspapers, and all usual starting points just came up blank," she said. "But I wanted to know the unanswerable: who was he and why did he do it? Was he inherently or psychologically unstable, or did the circumstances in his home life trigger something dangerous? I needed to find out what happened after Broadmoor."

Summerscale searched for months without finding anything until, remarkably, Robert - in the form of a gravestone - resurfaced in Australia.

"The photograph of his gravestone not only gave me that extremely helpful information - that he'd immigrated - but also the battalions he'd served in during the war, as well as the name of the person who'd erected the stone," Summerscale said. "I finally had the name of someone who'd known Robert at the time he died in 1949."

As she followed Robert's life to Australia, the contradictions continued.

Summerscale learnt Robert served in Gallipolli as a stretcher bearer during the First World War and that, after the war, he'd saved the life of a small boy called Harry Mulville who lived next door to Robert's farm.

"The stretcher bearers in Gallipoli were the most courageous," Summerscale said. "They would run completely unarmed out onto the field of battle to rescue people and to retrieve the bodies of the dead."

She wondered how it felt, for the man who'd once been responsible for such horror, to see similar carnage and play the opposite role: one of a saviour, as opposed to a killer.

"Out on the ridges of Gallipoli, a lot of the testimony talks about the terrible heat and stench of the bodies with the flies gathering on them," Summerscale said. "The scene wasn't so dissimilar to the house in London in Summer of 1895 when Robert had let his own mother's body rot. But here he was intervening to tend to the wounded and take the dead for burial. It was like a mirror-image. It must have been extremely weird, not to say traumatic."

Then there was the family of Harry Mulville. Cold calling numbers from the Yellow Pages and Summerscale found Mulville's children, learning that Mulville himself was still alive though well into his 90s.

"When Harry was 11, he was beaten so badly by his step-father that he walked himself to a police station and was sent to hospital where he spent a week," Summerscale said. "When I met Harry he showed me the scars of that beating that had happened more than 80 years before. Robert and Harry's mother - who had also immigrated from East London - arranged that Harry should stay with Robert, on the neighbouring farm, instead."

"Harry had a huge amount of respect for Robert Coombes as an educated self-disciplined, honourable man as well as affection and gratitude."

Is it a tale of redemption? Of regret? Summerscale doesn't feel the need to extrapolate a wider message from Robert's story, but her feeling upon uncovering the rest of Robert's life was one of relief.

"I'd given so much time and energy to Robert's story with the hope there was more to it than just a black psycho character. I'd hoped there'd be more depth and more dimension," she said.

"In the end, he found a way that was a happier and more generous. He began rescuing people from violence as opposed to inflicting it. If I were forced to draw a conclusion, I would say the story of Robert Coombes shows how, given enough love and care and safety, people who do bad things can also do much good."

To purchase a copy of The Wicked Boy, click here.

For more true crime, and the missing women who were never found, click here.

To read about the Victorian hairdresser murders that still baffle police 26 years on, click here.