The APS was introduced in 1988 as one of a number of reforms to the Prison Service, known as Fresh Start. The scheme resembles the police's graduate programme, and the aim is similar: to bring a stronger flow of recruits, with the potential for senior management, into the service. "We felt we had to get talent into the governor grades quickly," says governor Vicky O'Dea, APS officer at Prison Service headquarters. "Seven to 12 years was far too long."
Graduates start on the lowest rung of the ladder, as prison officers. Recruits spend two weeks observing life at their first prison, then a spell at the Prison Service college is followed by nine months on operational duties. This means working on the wings, directly with prisoners: unlocking cells, supervising work, escorting inmates to courts or hospital.
Officers on the accelerated promotion scheme skip the next grade, senior officer, and move directly to principal officer. This is a uniformed post, managing an area of the prison, perhaps a wing, or a task such as security. A principal officer has responsibility for staff as well as prisoners. Promotion, however, is not automatic: it depends on passing first the exam for senior officer, and then the principal officer promotion board.
Officers on the APS face a stiff learning curve, especially in their time as a principal officer. Often, APS members are managing colleagues who are older and more experienced than them.
Joanna Smith has just taken up her post as principal officer at the category- B prison Garth, near Preston. Aged 26, she studied psychology at the University of Central Lancashire. She spent six months travelling and 18 months working in a shop, before joining the service. Her first posting was to Lancaster Farms, a young offenders' institution.
As a principal officer, Ms Smith is responsible for two wings, managing its resources, especially the staff. She deals with security, staff shortages or illness, and prisoner welfare. She describes her job as "the link between the management and the staff".
A principal officer serves for a year before sitting the promotion board for "governor 5", the first rung of senior management and a non-uniformed post. Most prisons have several managers at governor grades, headed by the governing governor, usually at the highest, governor 1, rank.
Passing the promotion board is followed by more time at the Prison Service's college, then a year in a role away from a prison. This could be at the Prison Service headquarters, or in an area management team. After this, officers on the APS take operational posts at governor 5 level in a prison. Promotion to governor 4 means leaving the scheme, but the prison service expects its APS graduates to reach governor 2 within a further five to 10 years, when they might still be in their early thirties.
Jon Parkin is a governor 5 at Wymott Prison, also in Lancashire. Wymott's 800 inmates include category-C prisoners and sex offenders; the prison is a national centre for treating sex offenders.
Mr Parkin is a graduate, but joined the Prison Service as a prison officer in 1983, starting his career at Risley, Cheshire. He applied to the APS when it started, as an internal candidate. Now aged 35, he followed his time at Risley with a spell in the service's market-testing support unit. He is also one of two authors of the service's suicide-awareness package.
At Wymott, most of Mr Parkin's day-to-day work is individual rather than managerial. Much of it is prisoner casework that needs to be handled at governor level: parole, risk assessment, security categorisation, and dealing with litigation or complaints. He describes the work as "quasi- judicial".
Although he has a desk job, governors such as Mr Parkin still have contact with inmates. He walks the wings of the prison daily, talking to staff and prisoners and listening to any complaints. But there is a harder side to the job, too. Mr Parkin is trained as a riot control commander and can - and has been - called on to lead prison officers into a conflict situation.
This contrast is one of the factors that makes the Prison Service an environment that might not suit everybody. APS graduates can be given a hard time by older prison officers, some of whom are resistant to change. Managing prisoners is an art in itself.
"The challenge is that if you work for Tesco, most of Tesco's customers want to be there," Mr Parkin explains. "Most of our people don't want to be here."
The stresses can continue into outside life, too. Prison officers have to work shifts, and although the service tries to keep officers within the same region early in their careers, governors may have to move anywhere in England or Wales. Prisons are also very much in the public eye, yet few members of the public know how they operate.
According to serving graduates, friends and, especially, families are not always immediately supportive of their career choice.
Jon Parkin admits his parents were horrified when he told them, although they have come round. Joanna Smith says her job polarises acquaintances: they are either fascinated, or dismissive.
"People don't have a lot of awareness of what happens in a prison," Smith admits. "People don't really understand what we do. They think an officer is just about locking doors, but it is far more than that."
For her own part, Ms Smith says that she is motivated by a strong interest in criminal justice, as well as a desire to make a difference in society. "It is not just about punishment, but rehabilitation in a positive regime," she says. "It is about what we should be doing to stop people coming back when they are released"