HEALTH interventions by governments are a good thing, and the ability to use the financial clout of the Exchequer can be an immense force for public good.

Higher taxes on alcohol and cigarettes have played a part in cutting consumption, as has the ban on smoking in public places. Indeed, the very notion of repealing the latter initiative, which was resisted tooth and nail by the tobacco industry, has become unimaginable.

Duties on "beer and fags" are a staple of Budgets, so the call at a conference organised by the Royal College of Physicians of Edinburgh for a tax on soft drinks with a high sugar content has logic on its side. Evidence is cited from Mexico, where a tax increase resulted in a direct fall-off in consumption, with revenues ploughed back into health services to combat the effects of obesity.

"The successful introduction of sugar taxes in countries as diverse as Finland, France, Hungary, Latvia, the USA and Mexico have shown how effective a measure they can be in reducing consumption," said Professor Simon Capewell of Liverpool University.

"Furthermore, the revenues raised can then be invested back into initiatives to increase children's health in these countries, as is happening in Mexico."

We agree with all of this and support Professor Derek Bell, president of the Royal College, when he says: "Food and drink taxes are an important part of the discussion on obesity and public health more widely."۬But no-one should imagine that this will be easy or straightforward. There was impeccable logic to levying tax directly according to the strength by volume of alcohol but, while minimum unit pricing is on the Holyrood Statute Book, it is still being resisted by powerful vested interests, not least the Scotch Whisky Association.

Victories are possible. The tobacco ban in public places has been joined by the display ban at point of sale but the industry fights such measures and others such as plain packaging every inch of the way.

If the experience in Mexico proves accurate we should look at raising taxes on sugary, carbonated drinks, while being aware that we have the additional problem of the competing competences of Holyrood and Westminster.

And when Professor Bell mentions fatty foods too, we should recognise that even simple, clear and transparent packaging on fat and salt levels in foods such as the traffic light system has been fudged and resisted by the sector.

This is not intended as a counsel of despair. A healthier diet and better lifestyle encouraged through taxes is a worthy aim, but it will not be easy, it will not be quick and it will test the boundaries between state aspiration and individual choice.