ON September 9 1946 - 59 years ago this week - a train steamed out of Sofia station, taking with it the ousted royal family of Bulgaria, and the last vestiges of the extraordinary monarchy headed by Boris III.

Born Boris Klemens Robert Maria Pius Ludwig Stanislaus Xaver on January 30 1894, the son of Bulgarian king Ferdinand and Maria Luisa of Bourbon-Parma, the boy received the title Prince of Turnovo. At the age of 24, he came to the throne after his father was made to take the blame for Bulgaria's reverses in the 1913 Second Balkan War and World War 1, and abdicate.

As Boris III began his reign, Bulgaria was in political ferment. There was national frustration about the country having lost territories, having to pay huge reparations, and having had to drastically reduce its military strength. The Agrarian Union and the Communist Party wanted the monarchy abolished. The Agrarian Union's Alexander Stamboliiski became prime minister in 1919, pursuing - in authoritarian fashion - policies that were supported by the country's peasant underclass, but that were unwelcome among the middle class and  military. In 1923, the military toppled Stamboliiski, and for a few brief years there was a period of liberalisation. Another coup in 1934 saw the military bestow on Boris totalitarian power.

What kind of person found himself wielding this power? Historians have read his character in differing ways. Some write with sympathy of his ability to connect with ordinary people, of his humility, his understated nature, his caution, and of his boyish delight in driving trains. Others have emphasised his dexterity as a politician, his ability to manipulate people and powerful forces, and the apparent ease with which he transformed himself into a dictatorial ruler.

In the meantime, amid the political drama, Boris furthered his family life and his dynasty, marrying Giovanna of Savoy (daughter of Vittorio Emanuele III of Savoy and Princess Elena of Montenegro) in 1930, and fathering Maria Luisa (1933) and Simeon (1937).

When Hitler and his henchmen drew the war clouds over Europe, Bulgaria at first pursued a policy of neutrality, but then, under pressure from Germany's military and economic might, moved ever closer to the regime in Berlin. The situation was difficult. Many Bulgarians felt an affinity with Russians; but many of its political elite were orientated towards Paris and London.

Boris III found his popularity enhanced when, in 1940, he used his country's relations with the Axis to prevail on Romania to cede southern Dobroudja to Bulgaria.

Critical mass was reached in early 1941, as the Nazis advanced through Romania on their way to Greece, thus moving ever nearer to Bulgaria. Bulgaria quickly formally allied itself to Berlin. The situation became ever worse for Bulgaria, and for Boris. After the Nazis turned on the Soviet Union, bands of Bulgarian communist partisans attacked Reich troops. Boris declined to allow Bulgarian troops against the Soviet Union, so that they would not be called on to fight their "fellow Slavs". From January 1943, Allied bombers rained destruction on Sofia. Most vexed of all was the question of the fate of Bulgaria's Jewish population. While Bulgaria initially aped Nazi Germany by adopting anti-Semitic laws, courageous initiatives by some church and political figures led to attempts to reverse these laws, and a successful halt to attempts to deport Jews to Nazi death camps. Historians offer varying interpretations of the extent of the role that Boris played in saving the Jews of Bulgaria from mass murder. Some have held that he followed the lead set by others. Other accounts, including the diary of his former secretary, have suggested that his role was far stronger, and that far from just standing up symbolically to the Nazi death machine, he took other initiatives, including personally arranging travel documents and other means of escape.

What is inarguable is that, in August 1943, Boris was summoned to Berlin by Hitler, and subjected to a tirade about Bulgaria not fighting on the Eastern Front, and not allowing the deportation of Bulgarian Jews. What is equally inarguable is that, very soon after his return to Bulgaria, Boris, then aged 49, died while hiking in the Rila Mountains. The death certificate recorded that an autopsy had found the cause to be heart failure.

Some believe his death was caused by poison at the hands of the Nazis. Others have blamed the communists. A minority school of thought (variously said to have been inspired either by the Nazis or the communists) blames his family. Boris was buried at the Rila Monastery, but when the communists took power the remains were moved to the Vrana Palace. A post-communist medical examination of his embalmed heart was reported to have confirmed that death was caused by heart failure, perhaps brought on by stress. His heart was re-interred at Rila.

The current Bulgarian constitution makes no provision for a monarchy. Boris's son, Simeon, was six when he and his family went into exile, after a brief regency which ended in the train ride from Sofia, through a series of stations where the child was variously ignored, sometimes the object of warmth or curiosity. In some places, journalists tried to hound the "boy king" for interviews. Simeon Saxe-Coburg, having been denied an attempt to become President on the grounds that he had not lived in the country continuously for five years, came to power as Prime Minister in 2001 in a country that would have been hardly recognisable to his father. While Saxe-Coburg's party failed to win a second term in the 2005 elections, Simeon has the consolation of the extensive properties once enjoyed by his family and his father, awarded to Simeon through the post-communist property restitution process. For the rest, it remains to historians that wrestle with the questions surrounding the reign of Boris III.