Lincolnshire police run a seven-week course of Knight School for children who are on the brink of becoming unruly, nominated by teachers in local primary schools.
Sergeant Gary Brown, founder of the scheme and a specialist in medieval history, has trained more than 100 children from the market town of Spilsby to be proud, courteous and respectful towards others.
Sergeant Brown said, 'I take on three children with behavioural problems and nine well-adjusted children. I think this is the most productive way to run the course.
'The course teaches them about values, hygiene, safety and nutrition. The feedback we've had from teachers and parents is that there has been a remarkable improvement in behaviour. And this, in turn, has had a positive impact on the wider community.
During the training, the children wear medieval costumes, take part in community projects and, with the help of their parents, learn how to smarten their appearance and improve their manners.
The children also produce a weekly report on their parents' behaviour.
Sergeant Brown said, 'If parents behave badly - or swear a lot - this could jeopardise their child's place on the course.'
After passing the course the children are 'knighted' at Tattershall Castle, and presented with a wooden sword and shield.
The scheme, which has been funded by the police, the town council and the Rotary Club, has been so successful that five neighbouring towns plan to adopt it.