A highly-controversial multi-million pound plan to build secure colleges for young offenders has been abandoned by the Government.
Justice Minister Andrew Selous said all work on a pilot facility in Leicestershire with room for 300 12 to 17-year-olds had ceased.
The Ministry of Justice said last month that £5.6 million had already been spent on the project.
Hailed by ministers as a way to improve education in the system, it provoked widespread criticism among penal reformers and led to a string of Government defeats in the House of Lords.
Mr Selous said the plug had been pulled because the falling number of young people being detained made it unworkable.
"The coalition Government originally legislated for secure colleges as a way to deliver better education in the youth justice system," he said.
"This Government is also completely committed to improving the quality of education enjoyed by young offenders. This is one of the Government's top priorities.
"But the nature of the challenge has changed. The youth custody population has fallen from 1,349 in January 2013 to 999 in April 2015, a fall of 26%.
"A secure college could have been desirable with a larger population, but it would not be right to house one third of the entire youth offender population in one setting. It would also be a mistake to press ahead with such a development when resources are so tight.
"We are therefore not going ahead with the creation of a secure college pathfinder. All work on the proposed secure college pathfinder at Glen Parva has now ceased."
The latest MoJ figures show that up to the end of April, just over £4 million had been spent on design fees and site preparation and another £1.56 million on staff pay, procurement and other resource costs.
Andrew Neilson, director of campaigns at the Howard League for Penal Reform, welcomed victory in a long campaign it waged with other charities against the proposal.
"As Lord Ramsbotham and many other peers raised when these proposals were debated in the Lords, building a super-sized child prison and expecting it to reinvent custody with a dash of education was always misguided," he said.
"The Ministry of Justice is absolutely right to point to the success in recent years of driving down the numbers of children in custody, making the notion of housing a third of all those left behind bars in one facility anachronistic at best.
"At a time of straitened finances, it is far better to invest in preventing crime and keeping children safe rather than throw good money after bad on a failed project which never commanded confidence from experts in the field."
Shadow justice secretary Lord Falconer called the abandonment "a victory for common sense".
"The Secure College was a flawed idea that should never have made it off the drawing board," he said.
"Everyone agrees that more needs to be done to tackle youth re-offending, but Labour and criminal justice experts warned that this untested and potentially dangerous institution would do little to help with rehabilitation.
"Instead of wasting taxpayers' money on vanity projects, Ministers should now focus on improving the appalling conditions in our existing prison estate."