Who was Peter Manuel? The real story of In Plain Sight’s notorious serial killer

ITV's new real crime drama tells the story of the Scottish murderer played by Martin Compston and Detective Muncie's quest to bring him to justice


“If you didn’t put ‘This is a true story’ at the start of this, you wouldn’t believe it,” says Martin Compston, who stars as sinister serial killer Peter Manuel in ITV’s new crime drama In Plain Sight. 


The three-part series is based on the efforts of the determined Detective Muncie (Douglas Henshall) to prove Manuel’s guilt for a string of sexual assaults and murders near Glasgow. But it is a drama, not a documentary – so what is the true story of Manuel’s crime spree and how he was brought to justice?


What was Peter Manuel like as a child?

Born in New York in 1927 to Scottish parents, the youngster was brought to Scotland, before moving to Coventry with his family at the age of 11. He was bright and won a spot at a grammar school, but it wasn’t long before Manuel began acting out.

Convicted of “housebreaking”, he was sent to an “approved school” – that is, a boarding school for troubled kids. He absconded, so he was moved to another school, but he just kept running away.

At the age of 14, during one of his escapes, he showed early signs of the “Beast of Birkenshaw” he was to become. A report reads: “he was caught by the police, having broken into a house a few doors from the school and stolen a handbag. The lady of the house saw him coming from her bedroom with an axe in his hand. As a result she had a nervous breakdown.”


Less than a year later, Manuel was charged with three cases of breaking and entering and stealing, and one of malicious bodily harm when he struck a woman sleeping in her bed, causing concussion and haemorrhage. And then, at the age of 15, he was charged with indecently assaulting the wife of one of the school staff, knocking her on the head with a stick and attempting to rape her, stripping her, dragging her to the woods and hurting her so badly she needed eight stitches. Manuel pleaded guilty to robbery with violence. 

Ultimately he was sent to Borstal in England in 1943 at the age of 16, where he remained until 1945. Reports from the Borstal call him a “slippery customer”. At 18 he moved to Birkenshaw in Scotland to live with his parents. 

Why was Peter Manuel sent to prison the first time?


After a brief stint in Blackpool working on a fairground stall, Manuel was back in Scotland. In March 1946, he was sentenced to one year’s imprisonment for housebreaking and eight years for rape committed while on bail.

According to his psychiatric report, “he states that this was a trumped-up charge on the part of the police who, he infers, manufactured the evidence that convicted him. He states that from then on he had it in for the police who had framed him.”

The detective who sent him down was Muncie – and Manuel never forgot it. 

Did he threaten Detective Muncie?


Court reports reveal that he tried to send a letter to “McKenzie” from the Lanarkshire police – Muncie? – promising: “He is going to get it. Next time you see him remind him that he has a wife and kids. He will understand.”

It is also true that he sent Christmas and birthday cards to keep Muncie on his toes.

When was he released from prison?

In October 1952, Manuel was freed from prison. According to an account of his life in the court papers, he then worked for British Railways for two and a half years, but was fired when his criminal background came to light.

Back living with his parents, he worked with the Scottish Gas Board with his father until October 1956, when he was convicted of housebreaking and – after four years of freedom – was put back in jail, where he remained until November 1957. 

What really happened to Mary McLauchlan?


Episode one focuses on the fate of poor Mary McLauchlan, who is taken on her way back from a dance, dragged into a field by Manuel and sexually assaulted. But after conducting his own defence, the manipulative criminal spins a story and the case is “not proven”, after which Muncie promises McLauchlan that he will bring Manuel to justice. 

This is based on an incident in 1955 when Manuel did indeed successfully conduct his own defence on a rape charge at Airdrie Sheriff Court. McLaughlan, 29, testified against him and told the court he had threatened to kill her by decapitation. According to her evidence, Manuel appeared to gain pleasure from her fear, keeping her with him for around an hour and detailing how he planned to murder her, all while groping and kissing her. 

When did he first kill?

Perhaps emboldened by his acquittal (or troubled by the risk involved in leaving his victims alive), Manuel’s first murder that we know of was Anne Kneilands, 17, who he raped and bludgeoned to death on an East Kilbride golf course. 

In Plain Sight shows the doomed teenager enjoying herself at a dance hall before her death, but actually Kneilands never made it that far: her date had a hangover and didn’t turn up to her friend’s house, so instead she headed home. She was then stalked and brutally beaten by Manuel. 

The body was found in January 1956, but it took two more years for Manuel to be brought to justice.Although Manuel was a known sex offender who had been working locally laying mains pipes for the gas board, and although he turned up to work on 4th January with scratch marks on his face, and although some of his clothes were missing, Lanarkshire Police did not have enough evidence to charge him.

His father provided an alibi – and that was that. 

The killer strikes again 

Nine months later, Manuel committed murder again – this time upping the ante and taking three lives. On 17th September 1956 he entered the bungalow of Marion Watt, 45, her 16-year-old daughter Vivienne and her sister Margaret Brown in High Burnside and shot them all. 

Marion Watt’s husband, William, was on a fishing trip at the time. He was arrested and charged with the murder of his own family, having supposedly made an overnight round trip to cover his tracks. The police (except, perhaps, for Muncie) were convinced William was the culprit, and he was picked out of a line-up by two witnesses who claimed to have seen him en route.


He spent over two months in Barlinnie Prison, but was released due to lack of evidence. In fact, William’s case was even helped by letters to his lawyer from Manuel, who claimed a fellow prisoner had confessed to the crime and provided details only the killer could know.

Meanwhile, Manuel found himself locked up in the same prison after his conviction for housebreaking. But after his release in November 1957, he was free to kill again.

A taxi driver, a teenager and the Smart family 

In December, Manuel likely killed a taxi driver from Newcastle named Sydney Dunn, who was found dead on the Northumberland moorland with bullet holes and a slit throat. While he was later found posthumously guilty of the crime and a button from his jacket was found in the cab, there are some doubts about the case and whether the true murderer had been found. Either way, this murder has been completely excluded from In Plain Sight. 

There is no doubt, however, about the next one. Isabelle Cooke, 17, went missing on her way to meet her boyfriend on 28th December. There was an extensive search but police couldn’t find her body.

Then, in the early hours of New Year’s Day, Manuel struck for the final time. As in the Watt murders, he shot three members of the Smart family as they slept: Peter Smart, his wife Doris and their young son Michael. The bodies were not discovered until 6th January.

Astonishingly, their killer then stuck around the house, eating the Smarts’ food and feeding their cat while they lay dead. He even used their car, and gave a lift to an unsuspecting policeman who was on his way to join the Cooke search party. Manuel seemed to be getting bolder. 

How did the police uncover Peter Manuel’s crimes?


Manuel slipped up. A barman in a Glasgow pub became wary when a suspicious customer used new banknotes to pay for drinks – very unusual at the time. The police traced the serial numbers and – lo and behold – they had been withdrawn from the bank by Peter Smart before his death. 

After being arrested, Manuel led the police to where he had buried Cooke’s body. Taking detectives into a field, he reportedly told police: “You’re standing on her.”

Manuel initially maintained his innocence. But the police finally found leverage, taking his father in on a lesser charge. This prompted a confession from the serial murderer, who admitted to eight of the murders (he never accepted responsibility for the taxi driver).

The killer, who fancied himself as a bit of a law expert, represented himself in court – and pleaded not guilty. Despite an impressive show, the jury took three hours to convict him.

Though it is possible Manuel killed up to 15 people, he was convicted for seven murders: Kneilands’ murder was ruled inadmissible.

Was Peter Manuel suffering from mental illness – and was he a psychopath?


This was a point of vital importance to the trial, especially after Manuel’s conviction when he suddenly seemed inclined to argue that he was insane and put on a show of twitching and gazing around vacantly.

Belatedly, he told doctors that he had been struck on the head by a fragment of a flying bomb and had been severely electrocuted in an accident at work. This, he said, had led to some lapses of memory. But doctors found no evidence of epilepsy or any damage or neurological conditions.

Manuel is generally believed to have been a psychopath. In 1951, a Dr G.E. Swinney concluded: “His is an aggressive psychopath. It is doubtful whether, even at the beginning of his sentence, any constructive work could have been done with him.” Later reports also concluded he was a psychopath and “many of the crimes he committed had abnormal aspects.”

But psychopathy was not a criminal defence, and repeated medical and psychiatric examinations found him sane and fit for trial.

How did Peter Manuel die?


Manuel was convicted in May at the High Court in Glasgow. His appeal failed in June, and he was hanged at Barlinnie Prison on 11th July 1958, becoming the third-last criminal to be executed in Scotland. His last words were alleged to be: “Turn up the radio and I’ll go quietly.” He died at 8.05am.


During his 30 years of life, this sadistic murderer had traumatised his local community, killing almost a third of all the people murdered in Scotland in the years 1956 to 1958.