Spalding murders: Daughter Kim Edwards named as killer Published duration 9 June 2017

media caption Teenage sweethearts had 'dark dreams'

The couple believed to be Britain's youngest double murderers have been named, after a judge lifted a ban on identifying them.

Kim Edwards and her boyfriend Lucas Markham murdered Edwards' mother Elizabeth, 49, and her younger sister Katie, 13, at their home in Spalding, Lincolnshire, in April 2016.

The killers, who were 14 at the time, were both jailed in November.

A bid to stop their names being made public was rejected in the High Court.

image caption Elizabeth Edwards, 49, and her daughter Katie, 13, were found dead in April 2016

Edwards and Markham were originally jailed for at least 20 years each, but judges have reduced the sentences to 17 and a half years.

Markham, who admitted the killings, used a kitchen knife to stab both victims in the neck a total of ten times as they slept.

Edwards, who helped to plan the "cold, calculated and callous" killings, denied murder, claiming to be suffering a mental abnormality which impaired her ability to form rational judgments, but was found guilty by a jury

media caption Edwards: 'I never got on with my mum'

The teenagers were both jailed for life at Nottingham Crown Court in November and told they must serve at least 20 years before being considered for parole.

The court heard Markham walked for around 30 minutes along Spalding's Coronation Channel to reach Edwards' home before knocking three times on a bedroom window as a pre-arranged signal that he had arrived.

Edwards then opened a bathroom window to allow Markham to climb into the house from the roof of a shed, and gave him advice on moving quietly around the property.

image copyright PA image caption Police discovered the bodies of Mrs Edwards and her daughter Katie at their home in Dawson Avenue, Spalding

Evidence heard in the trial, but unpublished until now, revealed that the couple remained at the house in Dawson Avenue immediately after the killings where they had sex, shared a bath and watched the vampire-themed teen romance Twilight films.

They were discovered and arrested at the home Edwards shared with her mother and sister 36 hours later, having been reported missing to police.

Danny Savage, BBC North of England Correspondent

Kim Edwards and Lucas Markham planned a double murder born out of an intense relationship.

Kim resented her mother, Elizabeth, and disliked her sister, Katie, for the close relationship she had with their mum.

Drawn together by suicidal thoughts the couple convinced each the solution to the grudge she held against her mum was to kill her and her teenage sister.

Lucas wounded Mrs Edwards terribly before smothering her with a pillow. It wasn't quick - she struggled and fought for her life while Kim watched on.

Despite Kim's reservations about killing her sister, they weren't strong enough to stop Markham.

The details of the murders are some of the most harrowing I have heard in 17 years of court reporting.

The ban on naming the two teenagers was lifted by Mr Justice Haddon-Cave on 8 December but their identities remained secret until now to allow their lawyers to appeal against the ruling.

Outlining his reasons for lifting the ban, the judge said: "It is impossible for the public properly to understand this case without knowing the identity of the defendants and that these murders took place in a closed family context.

"This singular fact informs and colours one's entire understanding of the case... unless one knows this singular fact, it is impossible to understand the true motive behind these murders."

image copyright LincoLnshire Police image caption Lucas Markham and Kim Edwards plotted the murders for days, their trial heard

Upholding the trial judge's view, the ban on naming the pair was lifted by Sir Brian Leveson, Mr Justice Blake and Mr Justice Lewis.

Sir Brian said: "In the circumstances of this case, notwithstanding that the appellants are only 15 years of age, we have no doubt that the lifting of reporting restrictions is in accordance with law, pursues a legitimate aim and is a reasonable and proportionate measure ... properly balancing the welfare of the appellants ... against the Article 10 rights of the press and the interests of the public."

image copyright SWNS image caption Elizabeth and Katie Edwards were stabbed in the throat as they slept

Det Supt Martin Holvey, of Lincolnshire Police, said the "horrific and brutal" murders had shocked the community and the naming of the teenage killers would only add to that.

"I'm sure that sense of disbelief and horror will be deepened now it is known that it was Elizabeth's own daughter who was responsible for plotting with her boyfriend to carry out the murders," he said.

He said the extra details now made public, including how the couple stayed in the house after the killings and the lack of remorse showed by Edwards and Markham, were "chilling".

"These new revelations will undoubtedly focus attention on Spalding once again. I would like to repeat sentiments I have made earlier, thanking the community for their cooperation throughout the case and paying tribute to the courage of Elizabeth and Katie's family," he said.

"They have endured a terrible ordeal and faced the additional anguish of knowing that this horrific crime was committed by a family member."