A scandal-hit youth offenders institution set to close and reopen as an adult prison “was allowed to fail for years”.

HMYOI Cookham Wood has come under increased scrutiny in recent years after high levels of violence among inmates and appalling conditions were uncovered.

In March, the prison and probation service announced children would be moved out of the scandal-hit facility and the site would reopen in the summer - but to house adult criminals.

Now a new report about Cookham Wood in Borstal, near Rochester has revealed managers had not been given advance warning about the decision to change to an adult prison.

And, despite some improvements, on average children are only being allowed out of their cells for three hours a day - with some being let out much less.

Cookham Wood has been plagued by issues over the years, with hundreds of inmate-made weapons found, severe concerns around safety for the boys and staff, and increasing staff resignations because they didn’t feel supported by senior leaders.

The latest inspection took place three weeks following the Ministry of Justice (MoJ) announcement the facility would be turned into an adult prison in March and said issues were allowed to get out of hand.

When it was conducted, the 120-inmate-capacity youth prison held only 33 boys - down from 77 at the last inspection - as many had been transferred to other institutions.

Those who turned 18 were sent to adult prisons, and some had finished their sentences and were released.

An inspection in April last year found the situation in Cookham Wood to be deteriorating and said cells were dirty, inmates and staff were unsafe, and isolations were rife.

A follow-up six months later found limited improvements despite calls for action.

The latest report has found there had been some progress, with a more cohesive management team, cleaner living areas and communal areas, and graffiti was no longer such a significant issue.

It also said the situation around the extent of isolation had improved but was still too high.

Previous reports had shown boys had been put into isolation for 23.5 hours a day, with little to no social interaction, and there were a recorded 184 instances of isolation in the six months prior.

The new report also showed a significant reduction to 109 instances in the last six months, and the number of weapons found also reduced from 228 to 132.

However, returning inspectors found an establishment in limbo.

In their report they were critical of the way the MoJ had handled the facility in the past, as well as the management of its transition to an adult prison.

Charlie Taylor, HM chief inspector of prisons, said: “Cookham Wood has been allowed to fail for years without concerted action to improve the conditions in which children were being held.

“What is needed is a coherent plan to improve the provision on offer to these children so they can go on to lead crime-free lives when they are released.”

The inspection took place three weeks after the announcement of the change and the inspector found staff had been told nothing about what they would do after the facility would close.

At the time of the inspection, investments into refurbishing residential units and installing new classrooms was in progress or had been completed very recently and new staff, including teachers and dozens of youth justice workers, had just started or were in training.

Inspectors said they were impressed by how well staff engaged with the inspection team and their evident care for the children during this period of uncertainty.

A Youth Custody spokesperson said: “This inspection took place following our decisive action to move children from Cookham Wood, but it is testament to the work of staff that the report notes progress in education as well as their care in supporting children and young people to move to new accommodation.

“This will provide the help they need to turn their backs on crime for good.”

HMYOI Cookham Wood is due to cease operations at the end of the month and will be refitted into an adult prison for use from the summer.