Triple murderer Nicholas Prosper will not be given a whole-life order after a bid to increase his sentence was dismissed at the Court of Appeal.
Prosper, 19, would have become the first person aged between 18 and 20 to be given a whole-life tariff if three senior judges had ruled that his sentence should be raised.
He was jailed in March for a minimum term of 49 years, less 188 days already spent in custody, after admitting killing his mother, Juliana Falcon, 48, and siblings Giselle Prosper, 13, and Kyle Prosper, 16, at their family flat in Luton, Bedfordshire, on September 13 2023.
He also admitted weapons charges after plotting a mass shooting at his former primary school in the town.
If he had succeeded, he would have carried out the first major school shooting in Britain since the 1996 massacre in Dunblane, Scotland, in which Thomas Hamilton murdered 16 children and a teacher before turning the gun on himself.
The Solicitor General referred his sentence to the Court of Appeal as “unduly lenient”, with barrister Tom Little KC, for the Solicitor General, stating that the case was “exceptional”.
Barristers for Prosper, who is due to be released in his late 60s at the earliest, said the sentence “cannot be said to be unduly lenient”.
In a ruling released on Wednesday afternoon, the Lady Chief Justice Baroness Carr, sitting with Mr Justice Goss and Mr Justice Wall, said that Prosper’s sentence was “itself a very severe sentence for a 19-year-old”.
She said: “These were undoubtedly offences of the utmost gravity, with multiple features incorporating disturbing, recurrent themes around school shootings.”
She continued: “Had the offender been 21 or over at the time of the offending, a whole-life order would undoubtedly have been made.”
She added that the sentencing judge, Mrs Justice Cheema-Grubb, was right to conclude that the “enhanced exceptionality test” of whether to pass a whole-life term on an 18-to-20-year-old was “not met on the facts”.

She said: “Parliament chose to set what is already a very high threshold for a whole-life order for an adult, even higher for a young offender.”
She concluded: “Appalling though these crimes were, we are not persuaded that anything less than a whole-life order was unduly lenient.”
Prosper watched proceedings via a video link from HMP Belmarsh.
Whole-life orders are reserved for the most serious offences, with those handed the tariffs including Louis De Zoysa, who murdered Metropolitan Police Sergeant Matt Ratana in 2020, and Kyle Clifford, who murdered his ex-partner Louise Hunt, her sister Hannah Hunt and mother Carol Hunt in 2024.
Rules were changed in 2022 to allow younger defendants aged 18 to 20 to receive whole-life orders in exceptional circumstances, but no one in that age bracket has received the sentence since then.