In the companies I’ve been studying that have moved to 4-day weeks, unions have played little or no role in setting working hour or working conditions. But unions historically have played a huge role in setting working hours, and that’s one reason unions in the UK and the Labour Party have advocated for a shorter week. Paddy Bettington, a founder of Labour 4 Day Week, explains this in his new essay “Why the Four-Day Week Matters:”

The five-day week, the eight-hour day, paid holiday, sick pay and maternity pay were all instituted by mass movements, trade unions and collective bargaining….

[W]hen John McDonnell announced Labour’s plans to move to a 32-hour week at this year’s conference, he was clear that the primary mechanism to achieve this would be freeing the unions to engage in collective bargaining once more.

In the coming months and years, the Labour Party will enter government and be forced to institute – and prioritise – the myriad elements of their political programme. The move to a 32-hour week mustn’t be seen by the left as a nicety dreamt up by policy wonks, but as an essential means to loosen the grip of capitalism and a necessary foundation of a socialist agenda.

In a previous essay, he made the case for union involvement in the push to 4-day weeks:

The four-day week is not a silver bullet, but does offer a simple way to tackle a range of issues that affect the entire country. It represents a way of redistributing efficiency gains of new technology – if we’re going to have more automated tasks, we need to make sure that workers see the benefit. It would address the unnecessary contradiction of underemployment and overwork existing side-by-side. It would allow undervalued domestic and care work – disproportionately undertaken by women in our economy – to be shared more equally. It would bring our typical working week in line with our more productive neighbours France and Germany. It can lessen the rampant work-consumption cycle that drives climate change. Most importantly, perhaps, it can offer people more control over their lives.

There are individual cases that show a shift is already happening: some companies from across the world employ a four-day week, of their own accord, and see positive results. But we can’t rely on the practices of a handful of enlightened companies. The transformation we want to bring about requires demand from below and responsive policy from above. Using existing democratic structures is key. The Labour Party and trade unions are not only the most effective (and obvious) institutions to play this role, but also the natural champions of such a policy.

Bettington’s right that unions in Europe and United States have played an important role historically in defining national policy and the rules under which large employers organized their workdays, and the pieces are a nice illustration of how working hours and labor power have been connected. And you can believe that when the Times comes out against it, one reason they do is is that they recognize that the campaign for a 4-day week could revitalize labor unions and attract voter to left-wing parties.