On the 150th anniversary of its establishment, it seems the TUC has refound its radicalism. It has proposed that with advances in technology – especially artificial intelligence – a four-day work week is within our grasp. The argument is that if the benefits of new technologies are to be evenly spread around, workers can have a shorter working week (without loss of pay) and productivity can be increased, as in the case of organisations in New Zealand and Sweden. It seems like a “win-win” situation for workers and employers alike.

Under a four-day week (equating to 28 hours), long working hours could become a distant memory, available employment spread out to reduce unemployment and underemployment, while management would be tasked with using technology and workers’ time at work to drastically improve Britain’s poor productivity. The argument made is that not only do happier workers make more productive workers but workers also feel more of a commitment to their employer under such working conditions. Traditionally, Britain’s competitive edge has been based on low wages, low skills and low investment meaning that, with consequent low productivity, long working hours for both workers and employers became essential. Most now agree this no longer gives the competitive edge it once did.

But if the TUC’s ambition is to be anything more than a laudable pipedream, then the force of argument will need to be supplemented by the argument of force. The experiences of both France and Germany in reducing their working weeks are instructive here.

In France, under the left-of-centre governments of François Mitterand in the early 1980s and Lionel Jospin in the late 1990s and early 2000s, the working week was reduced to 39 hours and then to 35 hours. Today, the 35-hour week law remains in place but it has increasingly been eroded by changes to what constitutes voluntary overtime. This is because working more than 35 hours is not outlawed as such. Rather, it is the point at which overtime payments kick in, so that an attempt to create an economic incentive not to raise labour costs by having workers working more than 35 hours is made.

However, opposition from employers, in particular, has meant that the 35-hour week has not become the settled will. Since the financial crash, parties in government of both the centre-left and centre-right have acceded to their demands to loosen the hold of the law on working hours. This is despite there being tax breaks for employers to implement the 35-hour working week.

In Germany, it is the union movement which has led the pressure for a shorter working week, especially the biggest and most powerful union, IG Metall. In the 1980s, the push was for the 35-hour (or five-day) working week. This was won through industrial action. This year, and again using industrial action, the union movement in Germany has started to gain the four-day week, led by IG Metall. In Britain, IG Metall’s sister union in engineering secured a 35-hour week in the late 1980s and early 1990s through its “Drive for 35” campaign using targeted strike action.

Combining the twin forces of compulsion (through legislative underpinning) and pressure on the shopfloor (through workplace union organisation) would seem to give the best chance of pushing ahead with such a radical agenda in Britain. The most obvious scenario in which a four-day week might be introduced would be if a Jeremy Corbyn-led Labour government was to win power.

The content of the manifesto which Labour fought the 2017 general election on and its endorsement of the Institute of Employment’s Manifesto for Labour Law indicate that a four-day week is compatible with these policies. Like many other of Labour’s radical proposals on work and employment, union and worker support will be necessary to make sure Corbyn and John McDonnell are able not only to enter 10 and 11 Downing Street but also have the requisite support to see the legislation implemented.

Arguments to convince employers of the benefits to themselves and to the overall productivity of the economy will be necessary but not sufficient. Neither will workers and their families knowing that they will benefit from a four-day week without loss of pay. Both the French and German examples strongly suggest that what will neutralise opposition and make capital out of latent support will be mobilising workers in their hundreds of thousands on the streets and in their workplaces.

If Britain crashes out of Europe without a suitable Brexit deal – one that protects workers’ jobs as the TUC insists – Labour may well find it has an opportunity sooner rather than later to implement such a proposal. This would mean the significant cuts to the working week – achieved at the behest of the TUC – in the 19th and 20th centuries could be followed by another significant one in the 21st century.

• Gregor Gall is a visiting professor of industrial relations at the University of Leeds, editor of the Scottish Left Review magazine and director of the Jimmy Reid Foundation thinktank