A t first glance it reads like a bad pitch from one of Lord Sugar's apprentices. "We have the scale to match your ambition," boasts One3One Solutions' glossy brochure, "Prison walls are no barrier to business."

But One3One is trying to square a circle which, if it can be achieved, would be enormously worthwhile. It is trying to give many more prisoners some kind of meaningful activity behind bars – training which is relevant when they are released while at the same time making money to reduce the overall cost of running the prison estate. But they have to do this without impacting on the local economy of the law-abiding.

The Ministry of Justice says One3One operates under a code of conduct to ensure that these problems do not arise. The code says that "work for offenders in prison must not be used as a direct replacement for existing jobs in the community."

This is hard to measure with any degree of certainty. Some 9,000 prisoners take part in some sort of work programme and the Government wants to almost double this in ten years.

That does not mean One3One and the Government should not try. But it also needs to be realistic. As on The Apprentice, over-ambition can lead to disaster.