Judge Stephen Tumim's visit to Reading, one month after the disturbances, echoed the findings of an internal inquiry that inmates had too much time on their hands given the prison's limited physical resources and had little organised occupation.
In one of four prison reports published yesterday, Judge Tumim said it was 'indefensible' that young men of 17 to 20 should be held somewhere like Reading, which does not have anywhere where sports can be played safely.
He criticised the prison service's decision to turn the Victorian jail from a community prison to a remand centre for young offenders - some from as far away as Avon and Somerset, making family visits almost impossible. As a local prison, Reading was notorious for its overcrowding. But its change to a remand centre had been carried out without additional finance, which meant significant improvement was impossible.
The judge, however, praised the prison's rapid return to normality after the disturbances - over which 23 inmates face charges of prison mutiny - the quality of the staff and staff-prisoner relationships.
Judge Tumim was also highly critical of the way in which young offenders were packed together in Lincoln prison. He blamed inadequate facilities and activities for a spate of bullying which had seen several young prisoners seeking protection under Rule 43 - isolation from most inmates - because of continued victimisation.
Hatfield Young Offender Institution was said to be generally 'impressive', despite bullying and absconding, while Gloucester prison was criticised for keeping prisoners locked in their cells for up to 17 hours a day.