She follows interventions ranging from anger management courses to drug and alcohol counselling.
The children are aged between 10 and 16 and most have been placed in the units following sentencing by the courts because they are too young to be placed in young offenders institutes.
With intensive staffing ratios and heavy security, the cost of each place is high, but if it works the benefits to society can be significant.
At one secure unit, on the outskirts of Bristol, Winifred follows 15-year-old Mitchell, who is admitted after trying to hang himself in a young offenders institute.
He was sentenced following a vicious robbery which left a younger boy hospitalised.
Mitchell blames cannabis and the wrong friends for the attack, and while locked up he works hard on addressing his behaviour.
He plans for a better life on his release but his old friends are waiting for him back home, and both his parents and staff at the secure unit worry about what will happen.
The number of secure units is falling, down from 28 earlier this decade to just 19 and with a further four scheduled to close in 2009.
The government is keen to examine alternatives to custody, including intensive fostering.
But how do outcomes compare over the long term and what proves to be effective in addressing offending behaviour?
Work that goes on in places like the Vinney Green secure unit in Bristol includes a great emphasis on vocational skills to equip teenagers who may have been excluded from mainstream schools.
Winifred examines these intensive efforts and talks to some of the youngsters and their families about what the future holds.