The sugar tax – we may yet get one. The Greens have always backed this. Labour was a bit cagey about it but the party seems to be moving on this.

It’s a tax that would be applied to fizzy drinks.

The Health Minister Jonathan Coleman isn’t interested in a sugar tax. He has consistently rejected calls for one. And the main reason that he gives is that there is no evidence to suggest a sugar tax would work.

This ‘no evidence’ line is starting to wear a bit thin.

Over and over again the government is using it - 'there's no evidence'.

Earlier this week the government said there was no evidence placing a levy on plastic bags would reduce usage.

And remember pepi-pods? The baby bassinets given to new parents who were likely to co-sleep with their children.The Ministry of Health said there was no evidence the bassinets would save babies' lives - when almost every health professional said they would. Eventually, the government did a U-turn. Thankfully.

But this "No evidence line" is starting to wear a bit thin – it's a cop out.

So lets look at what the Brits have done with their sugar tax.

They're introducing it in 2018. Why? Well that gives manufacturers time to reduce the amount of sugar in their drinks.

Drinks with more than 8 grams of sugar per 100 mils will be taxed at a higher rate then drinks with less than 5 grams.

So the sugar tax, in the first instance, is being used as an instrument for change.

Will it lead to a drop in consumption of sugary drinks? Will it change habits? Will it improve diets? Well, ultimately that's the goal but in the meantime we have dentists all over the country who are extracting rotten teeth from children's mouths. A dentist told me he was working in Auckland and that was all he was doing every day - sometimes removing every tooth from a child's mouth. The whole lot. And why? He said it was sugary drinks. It said it's an epidemic.

So use this sugar tax to inject some funding into our health system to combat the impact of high sugar diets - rotting teeth, obese children - the list goes on.

Because what is the alternative? Inaction. We do nothing. We just keep doing what we're doing and expect that change will come. Inaction, surely, is not an option.

National still won’t budge on this. The Greens have been all over it from day one. And Labour is slowly moving to a position of support on this. Annette King says she can see some merit in a sugar tax.

But surely what we can't be is politically inactive? Surely we can't be dormant on a national health issue like this?

I agree that a sugar tax won't solve childhood obesity. It won't see an end to rotting teeth.

It won't help the obese pre-schooler who I saw stuffed into a stroller at the mall recently - he was huge. So huge he couldn't walk. And on his lap was a two litre bottle of Coke and he was screaming his head off pointing at the ice-cream counter. And his parents were slowly wheeling him towards it. You can't help him. He's a product of appalling parenting. The impact he'll have on our health system will stretch into the hundreds of thousands of dollars.

But what a sugar tax will do is help to fund some of the fallout on our health system, or the revenue raised can be used to directly target obesity and its prevention.

But wherever you sit on this, inaction, surely, is not an option.