A 15-year-old girl believed to be one of Britain's youngest double murderers concocted a plan to brutally kill her own mother and sister, it can now be reported.

Kim Edwards roped in her boyfriend, Lucas Markham, to carry out the "brutal executions" of dinner lady Elizabeth Edwards, 49, and her daughter Katie as they slept at their home in Spalding, Lincolnshire last April.

The couple, likened to Bonnie and Clyde during their trial, had sex, shared a bath and watched four Twilight vampire films as they "revelled" after the killings.

The identities of the couple could not be reported throughout a trial at Nottingham Crown Court in 2016 because of their age, but restrictions on naming the pair were lifted by three judges at London's Court of Appeal.

The pair, who were both originally given 20-year minimum custodial terms, had them reduced by the judges to 17 and a half years each.

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."

He announced that, as a result of the court's decision, "the names of these two young people are now capable of being reported", allowing reporting of the "full facts and circumstances" surrounding the case.

Both defendants were given life sentences for the killings, which were planned in a McDonald's.

Prosecutor Peter Joyce told Edwards' trial that her sister and mother were stabbed a total of 10 times in a "cold, calculated and callous" onslaught at their home in Dawson Avenue.

Mr Joyce told jurors that 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.

Detective Superintendent Martin Holvey, of Lincolnshire Police, said in a statement after the Court of Appeal's ruling: "The judges have ruled that there is a strong public interest in the full facts of this exceptional case being known, meaning that Lucas Markham and Kim Edwards can now be named.

"The murders of Elizabeth and Katie Edwards were horrific and brutal and the whole country shared a sense of shock that two juveniles, who were only 14 years old at the time, could have carried out such a horrendous act.

"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.

"Evidence heard in court that was previously restricted can now be reported.

"These include details about the behaviour and actions of Kim Edwards and Lucas Markham afterwards, which was chilling.

"They remained downstairs in the house, watching TV and eating food, whilst the bodies were upstairs. They showed no remorse at all when they were eventually found by officers and during their police interviews.

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

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