Mann’s idea was to try it herself for a couple of weeks and observe the way people react. After all, most people might have the intention of being a little bit kinder, yet we feel that we are unable to muster up the willpower. So why is it so difficult to both give, and accept, kindness? And would it really pay off in the real world – or are we just too cynical in today’s society? Mann recorded the pleasures, and embarrassments, of that journey in her recent book – Paying It Forward : How One Cup of Coffee Could Change the World. (In the spirit of the book’s contents, Mann’s royalties from the book go to a charity for patients with muscular dystrophy.)

Like many people, Mann’s interest in everyday kindness started with a heart-warming post on her Facebook feed. Her American friend Debbie had been visiting a drive-through coffee shop only to find that the person ahead had already settled her bill. “She was so chuffed – it made her day,” says Mann. Straight away, she was intrigued by the philosophy’s potential – the idea that a single act of kindness could “have a knock-on effect, like the butterfly effect”, sending ripples of goodwill through the world.

As Mann started reading up on the subject, she found that the principle has a deep history. In Italy, wealthier Neapolitans have long embraced the tradition of buying a “caffe sospeso” in addition to their own, for someone who is less able to pay for the luxury. Benjamin Franklin is one of the most famous proponents of the idea. While lending some money to a friend, he explained: “I do not pretend to give such a deed; I only lend it to you; when you meet with another honest man in similar distress, you must pay me by lending this sum to him,” he wrote. “This is a trick of mine for doing a deal of good with a little money.”