Ten years ago the Labour-Liberal Democrat coalition at Holyrood was pursuing a self-proclaimed "war on neds", with more use of custodial options.

In 2006-2007, the last full year of the coalition, there was a daily average of nearly 1000 youngsters on remand or on sentence.

A decade on and the situation is dramatically different with new figures showing that there are just 399 men and women aged 21 or under in the country's prison system. In total, the number of young offenders locked up has more than halved since the SNP came to power.

Partly this is because the Scottish Government - not before time - has changed its justice policy and moved towards emphasising alternatives to custody. But there is another, more fundamental reason for the drop in the number of young people in custody - young people are simply committing less crime.

Everyone can welcome that news, but what nobody can do is offer a completely satisfactory explanation for why it has happened. There are theories of course. For a start, there are signs that, following the years of the binge culture, young people are drinking less (in the Glasgow area in the five years to 2013, accident and emergency admissions for underage drinkers fell by about 40 per cent).

Committing traditional forms of crime has also become harder for young people. In the 80s, joy-riding was relatively common for example but it is now much more difficult than it was to steal a car. The incentive to break into a house is also not what it once was as the kind of household goods up for grabs do not command a high price down the pub or on the black market.

The internet may also be playing a role in cutting youth crime for the simple reason that if young people are inside on their X-Box, they are less likely to be outside committing crime. There may also be an element of self-policing through social media - if a young person does commit a crime or behave in anti-social way, they are more likely to find themselves shamed than celebrated.

Whatever the explanation, the fall in crime and the consequential fall in the number of young people in custody offers positive possibilities for the justice system and wider society. With fewer young men and women locked up, it should be possible to offer them more intensive help than was feasible when the numbers were greater. Focus attention on those in custody and the chances are the numbers will fall even further.

However, no one should sit back and assume the problem is fixed because the fact youth offending is going down does not mean it will stay down. In fact, there is a danger we could see another rise in years to come if it is true there is a lag of ten years or so in how recession and austerity affect crime figures. It was not until ten years after the height of Thatcherism that the consequences were seen in a peak in crime in the mid 90s when the children of the 80s reached their teens and the same could happen again. We may be seeing falling crime figures now, but what happens when the children suffering under austerity now grow up?

when the children who are suffering most fro the austerity cuts of the Coalition government hit ther teens