On one level, the finding is counter-intuitive.

In the first week of Scotland's new, lower drink-driving limit coming into force, the expectation would be that the number of drivers caught over the limit would increase, particularly as the period coincided with the first seven days of Police Scotland's festive drink-driving campaign, when there are traditionally more risk-takers behind the wheel.

In fact, there was a 30 per cent drop in the number of drivers caught drink driving. The fall is all the more surprising given that the figure compares like with like with a week from last year's festive police campaign but with a weekly average. Surprising, then, but this is a trend that is no less welcome. Before the new limit was introduced on December 5, there were complaints about the nanny state interfering in an area where there were already enforceable limits on driver behaviour.

There are many examples of legislative intervention modifying behaviour for the better and the figures for week one suggest there is great potential for the new limits further improving road safety. It would be dangerous to read too much into them so early, of course, but there were already signs of drivers paying heed to the new limit when DIY electronic breathalyser kits started to sell out as the new regime came in.

It is one thing to self-test with a kit before getting behind the wheel. It is another conscientiously to decide not to take a chance. The week-one figures suggest that a greater number of drivers opted for that course of action, albeit there would have been an awareness of a heightened risk in drink driving because of the festive police campaign.

Public education campaigns do not always hit home but the Scottish Government's strategy to make the public aware of the new limit has had an early success, based on the week-one figures. It has been noticeable that motorway gantries have made drivers aware of the lower limit and this, along with other advertising, has had a trickle-down effect all the way to the water cooler, with colleagues discussing amounts that are safe or unsafe to drink, bearing in mind that they might not be driving until the next morning (in the first week, 10 per cent of the total were caught in the morning).

Social media has also been awash with online conversations about the new limit and even the controversy itself about perceived iniquities in the new, stricter policy has served to raise the policy's profile. That must be for the good. If drivers are drinking less, or not at all on a growing number of occasions, because of the new limit, the potential for long-term health gains is evident.

Cars and other forms of motorised transport are potentially lethal machines. Nearly one death in six on the roads involves drivers who are over the legal limit. Cutting that limit should, over time, reduce the number of drink-related road deaths, either by motorists heeding the warning or by making it more likely they will be caught and banned if they continue to drink and drive. The early signs point in the right direction.