Before venturing into journalism, I spent six years earning my keep as a retail worker. My first real job out of school (that is to say, something beyond a Saturday job at a car wash) was at a video game shop. I spent 18 months getting to grips with using a cash register and perfecting my polite customer service voice, before leaving for a role with one of the UK’s biggest supermarkets (which I’ll state is not the brand featured in this piece).

Those five-and-a-half years made it very clear that flexibility has always been integral to the retail environment. But to me and my fellow boots-on-the-ground, that focus seemed heavily skewed towards how employees could be flexible for the benefit of their bosses, rather than the other way around.

For example, while writing this feature, I recalled that in my five years at the supermarket, I had started at least one shift at every hour of the day. This work-life balance (or lack thereof) meant I struggled to progress in the management training scheme I’d been accepted into, and thus my chances of career progression were slim. I withdrew from the scheme and decided to apply for journalism school, and even then, the only way I was able to attend was by dropping to part-time hours.

So when M&S announced it was launching a four-day work week, the first thing that came to my mind was: “how”?

In an environment with ever-changing schedules and around-the-clock working patterns, would a four-day week be effective?

The next thought I had was: "why? What was M&S getting in return?"

To find out why and how, we spoke to Sarah Findlater, Group HRD at the retail giant.