One evening last week I was in the kitchen fixing myself a cup of tea when my son put his head around the door. I have hardly seen him since he left school last summer as he spends his days working in a sandwich shop and nights taking orders in a fast-food takeaway.

How’s it going?, I asked.

Good, he replied.

These jobs of yours, I said. Have they taught you anything interesting yet about or work, or life – or anything?

Yeah, he said. They’ve taught me I like getting paid.

My question was prompted by a recent Harvard Business Review blog arguing that humble jobs teach young people more about work than any amount of poncing around as an unpaid intern in a film production company. The author, who is now a law school professor, was once a busboy and a cleaner – jobs which he says taught him lessons that have come in handy ever since.

Already I was seeing the sense in his general argument. My son’s first key takeaway from the takeaway restaurant was spot on:

Getting paid really is nice. It is a pity most of us get so used to it that we forget to be pleased when payday comes around.

So what else had it taught him? He said he’d think about it and tell me later: he had to go or he’d be late for his evening shift. This led to the second revelation:

If you are earning £7 an hour, you need to work longer than an investment banker to make any money at all.

And that, in turn, led to the third:

Earning the minimum wage makes you grateful to live at home where there is a warm bed and full (ish) fridge. For everyone else, it is a game of survival and he doesn’t understand how they manage.

Later that evening I got a text from him saying the restaurant was quiet and that we could talk. So I went over to find the place entirely empty apart from my son, who was loafing around by the till. This led to his fourth revelation:

Doing nothing sucks. It’s the worst thing there is. It makes you so lethargic that when things get busier you can hardly bring yourself to budge.

Isn’t he also learning how to be professional, I asked – leading the witness outrageously.

Obvs, he replied. And then came lesson number five:

You have to be punctual. And reliable. You mustn’t swear, or turn your back on customers, or answer them back. If you have a hangover, you still have to get to work on time, and you have to pretend that you feel fine.

Listening to him recite this list led me to contribute an insight of my own:

A fast-food restaurant is an excellent finishing school. It has succeeded in areas where 18 years of liberal parenting and seven years of hugely expensive private education have made little impression.

Yet even though he has learnt how to be civil to customers, he has not learnt to like it. In fact what he has discovered is that:

Dealing with customers can suck. Some of them are friendly, but there are lots who don’t even look at you. That gets to you after a while.

My son looked anxiously at his watch and said his boss would be in soon. But I thought you told me you liked him, I protested.

He shrugged. “He’s okay. In the beginning, we went for a drink after the shift, but he decides how many hours I work, and he blames me for stuff like not ordering new menus, when that’s not even my job. So drinking with him feels weird.”

In other words he has learnt invaluable lesson number eight:

Being friends with your manager is never a good idea.

Before I left him, I told him that his lessons bore no resemblance to the ones drawn by the HBR blogger, whose stint doing humble jobs taught him great truths about humanity: that most people want to take pride in their work, and that everyone has big dreams.

What did he think of that? He pointed out it was hard to take pride in your work when the restaurant is doing badly and the manager doesn’t care. But even with good management, some people are still useless moaners, which led him to lesson nine.

Working with whingers is rubbish.

So what should be done about them, I asked. He looked at me as if I were an idiot.

“F***ing fire them,” he said, momentarily forgetting lesson #5.

And what about dreams? “Yeah,” he said. “Everyone here has dreams.”

Slightly dreading the answer, I asked what were his.

To my relief he replied: "To get into university and to get a skilled job."

– Copyright The Financial Times Limited 2013