The economist Virginia Minni followed ten years of data inside one large multinational roughly 200,000 employees and 30,000 managers, spread across a hundred countries. She found what you would expect: the best managers lifted their people's performance while they worked for them. The surprise was what happened afterwards. If a great boss were simply a good motivator, the gains should have faded once they left. They did not. People who had worked under the strongest managers were markedly around forty per cent more likely to make a successful internal move and their pay and progress carried on rising years later, in roles those managers had nothing to do with. So a manager is not the weather of your career, a spell you endure or enjoy and then forget. The right one quietly resets the slope of the whole line.

Across twenty-four years I can name only two managers who changed my trajectory, and it was never because they were easy to work for. It was because they handed me things I was not ready for and then refused to let me fail at them in private. I learned more in those stretches than in any course, and I am still drawing on it. I have also been someone's first manager and I hold that far more carefully since understanding what slope I might be setting.

We optimise the things that compare neatly: pay, title, brand. They fit in a spreadsheet. The manager is harder to measure, so we quietly discount it. But the evidence suggests the variable we can least quantify is the one that compounds the most and the only one that keeps paying out long after we have moved on.

It matters most at the beginning. A first manager sets the angle of everything that follows; a good one early, and the gains accrue for decades. Which is the cruel part — the people with the least power to choose their boss, those just entering work, carry the most riding on the choice.

So the next time you weigh a role, interview the manager as hard as they interview you. Ask how they grow the people who work for them, then ask two of those people what actually happened. The title will fade and the salary will reset at the next job. A good boss compounds, and follows you out of the door in the best possible way.