Claire Trevett: National's curfews and boot camps. Is the 6 o'clock swill next?

National's plan to fine parents of under-14-year-olds caught marauding in the wee sma's and slap youth offenders into a Waiouru winter for a boot camp is less about youth offending than getting votes.

Things like boot camps and curfews hark back to the olden days. What next? A return to the 6 o'clock swill?

The idea of a state-imposed curfew on those aged under 14 and fines for the parents of children who breach it is well adrift of National's usual approach that parents know best how to raise their kids and should be left to it.

Even Prime Minister Bill English admitted there was little evidence other than anecdotal of either the extent of it or the likely effectiveness of a fine approach. He simply concluded that even one 12-year-old wandering round in the middle of the night was too many and that was that.

There might be no evidence to back it up, but there is evidence that tough-talking law and order policies get votes.

In this case the targeted votes were National's own supporters concerned about crime and older voters who think the youth of today are missing out on good-old fashioned discipline. In other words, it is aimed at NZ First voters or those looking that way.

The very next day, National bookended its tough talk policy with a more considered $100 million package on mental health. It was an area Labour had made a lot of noise about, accusing National of presiding over big increases in mental health problems without enough action to address it.

That package was aimed at shoring up National's vote in the centre by reminding voters of the "compassionate conservatism" former Prime Minister John Key had preached but English was responsible for delivering under his "social investment" model. It was an attempt to show National still had a grip on what voters were concerned about.

This did have evidence behind it (some of it ignored, such as chief science adviser Peter Gluckman's plea for action on alcohol). It targeted a similar age range as the law and order policies - Health Minister Jonathan Coleman said half of all mental health problems were apparent by the age of 14.

But unlike the youth offenders' policy, it was a fully-fledged Government measure with funding allocated and ready to begin.

The "evidence" behind the law and order policies was more negligible.

They are based on the public reaction to media coverage of dairy robberies by young people and in Kaikohe earlier this year when a group of 12 to 14-year-olds went on the rampage. In the latter case, a fine approach might have backfired - it was the parents of the children who dobbed them in to Police. The prospect of a fine as a reward for that might have deterred them.

English made a more convincing case for the boot camps although a string of experts, including the PM's own science adviser, say evidence such an approach works is flimsy to non-existent.

English claimed the courses were more comprehensive, will involve education as well as physical training. He contended it was better than the alternative of prison or a youth justice facility which he sees as a Tricks of the Trade Academy where young crims learn tricks they need to become older crims.

Between them the two policies did at least kick Labour's leader Jacinda Ardern off the top of the news for a while. Ardern's counter-offer yesterday was a reheat of Labour's 2015 proposal to teach students to drive at school.

English's response to that? It was "half-thought through".