My career started in the 1970’s with a three day interview to assess whether I had the right qualities to join the armed forces. This involved the usual round of leaderless discussions, practical exercises and written papers, finishing with an interview board chaired by a senior officer. He began by asking me what I felt was the most important quality in a leader. I smiled brightly and replied ‘A sense of humour, Sir’, guessing that the board were tired of text book answers involving ‘integrity’ or ‘decisiveness’.

My guess was spectacularly wrong. After an ominous pause, the board attacked ‘en masse’ and I spent the rest of the interview defending my position. I passed, probably in spite of my views rather than because of them, but I now know that I was wrong. A sense of humour is a vital quality, but not the most important one. Years of leading men and women in dangerous situations has taught me that the most important thing is simple. It is to know yourself.

This ancient injunction, if fully understood, has significant ramifications. If you know yourself, you know your strengths and can work to them. You are also aware of your faults, and can find ways to manage them. Secondly, self knowledge is an antidote to the hubris which eventually seems to grip top leaders. They come to believe that they possess divine qualities: that they are immortal, all powerful and all knowing. Hubris comes before the fall.

Thirdly, while you can usually manage people below you in the organisation, all my experience is that you can never lead them unless you truly like them. You cannot like others unless you like yourself, and you cannot like yourself unless you understand your personality.

How, then, to acquire self knowledge? The first thing is to seek and listen to feedback from your family and close friends. They are usually the only people who will frankly tell you who you are, and how you are perceived. Such feedback needs to be coupled with regular reflection in solitude. Take some time every day to listen to the silence, to reflect on your past decisions and dream a little of the future. This will recharge the batteries and give you an understanding of the workings of your own mind, a vital step to self knowledge.

Another technique that I recommend is borrowed from successful bomb disposal operators. After every major event take some time to think through what went well, why and how that relates to your personality. Enjoy this – reinforcing what you do well is vital to your future effectiveness. Next reflect on what did not go well, how you would change it next time and, again, how this relates to your character.

Nowadays, I know myself better. I understand that the answer I gave to the board 30 odd years ago was driven by my love of being an iconoclast, and the defence of my position born from tenacity. Both of these are good leadership characteristics. I also know that, unless governed by reflection, these same traits can manifest themselves as bloody minded stubbornness. A sense of humour in a leader is far more appealing.