Thirty children are locked up overnight in Sussex Police cells each week, figures obtained by the Howard League for Penal Reform reveal.
New research by the charity shows that there were 1,564 overnight detentions of children aged 17 and under in police stations across the county during 2011.
The total across England and Wales was 40,716 – which equates to an average of 112 detentions per night.
However, the true number is likely to be far higher as some of the largest police services in the country were unable to provide figures.
The data shows that the number of overnight detentions is falling nationwide – a success for the Howard League’s campaign to reduce the number of children getting caught up in the criminal justice system.
But now the charity is calling for the practice of holding children overnight in police cells to be brought to an end altogether.
The Howard League is urging police to work more closely with parents and children’s services to provide safe and appropriate care for boys and girls who come to their attention.
A briefing paper published by the charity also calls for the presumption of bail to be strictly applied to children, as well as pushing for all police to be trained in safeguarding and child protection.
Frances Crook, chief executive of the Howard League for Penal Reform, said: “Holding children as young as ten in police cells overnight is unjustifiable. The vast majority of children who are locked up are innocent of any crime, and it is a frightening and intimidating experience which does more harm than good.
“It is encouraging to see that the number of detentions is falling nationwide, thanks in part to our successful campaigning. This is a victory for common sense, prudent use of police resources and improved community relations.
“But the number remains far too high and it is particularly worrying to see that practice varies widely from police service to police service.
“What boys and girls need in most cases is simply to go home. On rare occasions, somewhere safe – not somewhere secure – should be provided by the local authority.
“Parents, not police, should be taking responsibility for their children.
“Police are to be congratulated for the significant fall in the use of police cells in recent years. It is extravagantly expensive to detain children at a time of austerity, particularly when almost all of them are innocent, or have just been naughty and that behaviour can be dealt with quickly and safely by parents.”
In 2010, police services across England and Wales recorded more than 45,000 overnight detentions of children aged 17 and under.
The drop in detentions has coincided with a 15 per cent fall in the number of child arrests. Several police services have reviewed their arrest policies and procedures as a result of the Howard League’s positive engagement with them.
Over the two-year period, there were 387 overnight detentions of children of primary school age.
Girls accounted for 15 per cent of the total number of detentions.
The figures were presented to MPs yesterday (October 15) at a Howard League event at Westminster with Jacqui Cheer, the chief constable of Cleveland Police and the Association of Chief Police Officers’ lead on children and young people.