In the summer of 1886, King Ludwig II of Bavaria and his doctor went for a walk in the woods near the Starnberger See, a great lake near Munich. They never returned. The manic, but beloved, Ludwig and his doctor were found floating in the lake. A post-mortem examination showed that the King hadn’t died from drowning and his doctor had superficial injuries to his face. There were no other clues as to how they met their end.

A week before the fatal walk, senior members of the medical profession in Bavaria had been arrested on King Ludwig’s orders, as they had declared him insane and unfit to govern.

Most people probably have only a passing interest in manic depression, but it is the psyche of a nation’s leaders that determines not only its welfare and spirit, but its influence on the rest of the world. Ludwig may have emptied his country’s coffers and scandalised the prudes, but he encouraged Wagner and other musicians. He also promoted art art and architecture, and in doing so littered Bavaria with imaginative castles. Although reclusive, he came to life at night and, when in a manic mood but not involved in questionable behaviour with his court, would summon his sleigh and call upon his astounded subjects.

Most leaders have personality disorders, or they might not have stood out from the crowd to reach parliament and wouldn’t, once there, have climbed the casualty-strewn path to political heights. Apart from such disorders, some leaders have characteristics that show varying degrees of a psychiatric problem. Like Ludwig,Churchill — and, in the arts, Dickens, Mozart and Beethoven — were probably manic depressives. Manic depression, now often referred to as bipolar disorder, is the condition in which people will at different times either be acutely depressed or display overexuberant, extravagant manic behaviour.

People are likely to recognise a depressed mood, but manic behaviour is often misunderstood. Symptoms include overconfidence, marked self-esteem and even grandiosity. Sufferers’ minds tend to flit from subject to subject and scheme to scheme and, although easily distracted, they paradoxically become engrossed in some specific goal-orientated activity that consumes their thoughts. They are articulate (even loquacious), speak quickly, dominate the conversation, are agitated, need little sleep and in many cases are adept (when in a manic rather than depressed mood) at squeezing the last ounce of enjoyment out of a situation without thought of the consequences. They are spendthrift. They are also often talented artists, musicians and writers and, on average, have IQs 10 per cent higher than contemporaries.

Personality disorders are more difficult to diagnose, but most of us recognise when someone is unusual and doesn’t conform to the accepted pattern of behaviour, but is obviously sane. Wellington may well have had a schizoid personality disorder. He was indifferent to the praise or condemnation of others, had few confidants, appeared to be aloof, cold, and emotionally detached and rarely gave any evidence of strong emotional feelings. Some of our recent political leaders have fitted this description. Diagnosing personality disorders is a skill, but conformity has an internationally accepted guide, the DSM4. Making an accepted diagnosis is a box-ticking exercise; a certain percentage of the classic symptoms needs to be present.

The histrionic personality disorder found in some actors, lawyers, and old-fashioned parsons has eight characteristic symptoms. Four of these need to be present for a diagnosis. The essential features are that the person should:

1 — constantly seek approval and praise;

2 — dislike being anywhere where they are not the centre of attention;

3 — have shallow and vacillating emotions and beliefs;

4 — be self-centred and short-term planners, and be angry if frustrated;

5 — be inappropriately concerned with physical appearances and gestures;

6 — be overemotional when displaying grief or welcome.

7 — display sexual behaviour that is inappropriately adventurous;

8 — make speeches that sound impressive but lack substance and detail.

Most of us can think of one leader who would have more than four of these boxes ticked. But what about Gordon Brown? He is an unknown quantity but there are suggestions that, although highly intelligent, he has some of the emotional detachment of a Wellington and some of the pedantic obsessiveness of Captain Mainwaring, of Dad’s Army. Mainwaring had never been tested in battle, as Sergeant Wilson, who found Mainwaring difficult to work with, tactfully reminded him from time to time.