Hatfield Prison has been rated as "exceptional" by government inspectors, according to a new performance report.
A newly-released report from the Ministry of Justice shows that the male open prison was given the highest possible performance rating for 2017-18. It represents an improvement on the previous year, when inspectors said the prison was only meeting the majority of its targets.
Nationally, prisons were given higher ratings on average, but the Ministry of Justice said outcomes were not directly comparable with previous years due to a change in the framework. Issues with data reporting have meant that the extent of assault and self-harm in institutions may not historically have been fully recorded.
Frances Crook, the chief executive of the Howard League for Penal Reform, said this was a concern.
She said: “It is shameful that so many prisons are performing so poorly, with violence and self-injury again rising to new highs.
“Given we now know that prisons have been under-reporting assaults and self-injury incidents, the fear must be that some are faring even worse than the ratings indicate.
“On the horizon, however, we should see improvements in the next few years if the number of people in prison keeps falling.
“Further steps to reduce the prison population would save lives, protect staff and prevent more people being swept into deeper currents of crime, violence and despair.”
Across England and Wales, 14 of the 118 prisons assessed were considered to be "exceptional". At the other end of the scale, the performance of 15 was of serious concern.
The Ministry of Justice said that they are investing heavily in prisons and have recruited more than 3,000 additional officers as they aim to urgently improve conditions.
The prisons minister Rory Stewart said: “We need to get the basics right in prison, which is why we are giving them extra support to ensure they are safe, secure and decent.
“We recently announced an investment of £30 million to stabilise the estate, including £16 million dedicated to improving facilities at prisons with the most pressing problems – to help bring them up to the standard we expect.
“And our recruitment drive is vital to ensuring prisons can be places where offenders can be rehabilitated. We are well ahead of schedule, with 90 per cent of our new 3,111 prison officers due to be on landings this summer.”