The chief inspector of prisons has warned that pioneering therapeutic work at a south Devon jail is being threatened by the effects of overcrowding.
"Good work" was noted at Channings Wood prison
Anne Owers has just inspected Channings Wood and noted the "good work" being done there to reform sex offenders and drug addicts.
But she said the work is being compromised because it is having to take in unsuitable inmates due to overcrowding elsewhere.
The governor of Channings Wood prison, Nick Evans, said: "There's nothing we can do to alleviate it, but we have to find better ways of dealing with those prisoners while they are here.
"We may not be able to get them to use the facilities that we have to their advantage, but we have to find other ways of dealing with them, so instead of them being a problem for is, it's actually a positive aspect that we can perhaps use in another way."
Exeter Prison is still in the top 20 most overcrowded prisons, according to the figures.
Nationwide, the figures show the number of prisoners in England and Wales has reached a new record.
Exeter governor Ian Mulholland said cells designed for one inmate were being used by two.
The problem would be eased with plans to create another 100 spaces.
But he added: "City centre prisons are always going to be the most crowded because of the nature of the business that we do."
He said the key to cutting prison numbers was investing in training, employment and relationship issues.
"We have just launched a £250,000 resettlement strategy.
"We know that if these issues are settled, they are far less likely to come back to prison."
Mr Mulholland said Exeter was also being hit with an influx of prisoners from elsewhere.
"It's not ideal for those that are sent sometimes many hundreds of miles from home. In terms of reintegrating, its much more difficult to do miles from where they live, than close to home.
"When you have different factions of prisoners, the potential for unrest is also increased."