It is probably the least noticed social revolution of the 21^st century. At some point in the past decade, Britain has turned into a nation of part-timers.

Instead of putting in a full shift and striving every hour of the day to better ourselves, we have become a country that clocks off early, cuts back on our hours, and turns every weekend into a three or even four-day break.

There is nothing wrong with that in principle, and we all need to find the right balance between work and life. But these choices are not made independent of government policy. We have the wrong incentives, and that is going to prove very expensive for the wider economy. The data makes the transformation very clear. According to an analysis by this newspaper, employees are working 2.3 hours a week less on average than they were at the start of the century. Add them all up, and this is the equivalent of losing 1.7 million people from the workforce.

Just as significantly, hours are falling at the quickest rate among our most skilled, productive people, with the top 10 per cent of earners cutting their hours from 48 to 44 per week on average. The leaders who should be powering an economic revival are clocking off early and going to the gym or the golf course instead.

And yet, why should anyone be surprised? Successive chancellors have decided that work should not pay, especially at the top end of the earnings scale.

Frozen thresholds drag more people into the top rate; tapered personal allowances and child benefits mean it is often not worth making more than £100,000; and tax raids on pensions mean it often makes more sense to give money away than earn more.

However, every time someone cuts down on their hours at the office, shop or factory, we lose output, tax revenues and, perhaps more importantly, the dynamism that comes from driven, determined strivers working together towards an ambitious goal.

Britain faces plenty of challenges if we are ever to get our economy growing again. But one of the main ones will be this: we need to get the number of average hours worked back up again, and that will mean restoring incentives, and allowing people to keep more of what they earn.

If we fail to do that, we will be stuck in permanent, if leisurely, decline.