The public has long speculated about Vajiralongkorn’s finances, hot temper and other matters. Three failed marriages are a matter of public record.

“When you are born into this position you have to accept it,” he told the women’s magazine Dichan in a rare interview in 1987. “Some people like me, some people don’t like me. It’s their right ... Wherever you go there is gossip. If you are busy with gossip you don’t have to work.”

As crown prince and now as king, Vajiralongkorn has been protected by a Thai law mandating a prison term of three to 15 years for anyone found guilty of the loosely defined crime of insulting the monarchy. Prosecutions under the lèse-majesté law, and blocking of internet sites deemed insulting to the royal family, have grown more common in recent years.

Although he attended the requisite royal ceremonies and in recent years filled in for his father for some ceremonial and diplomatic duties, the prince is generally a private figure, visibly ill at ease in most public settings. His three sisters and first wife often appear on nightly television broadcasts of royal news, attending social functions and carrying out good works that burnish the monarchy’s reputation.

Vajiralongkorn’s appearances have been less frequent. While all the siblings travel abroad frequently, his sisters usually are promoting their homeland in one manner or another.

The prince’s activities are usually personal and unpublicised, outside of the occasional tabloid story in the country he is visiting. He has spent much of his time at residences in Germany, and returned from a stay there just ahead of becoming king on Thursday.

In 2015, he made two high-profile public appearances in Thailand, leading thousands of people in mass bicycling events to mark the birthdays of his mother and father. Many saw the events as an attempt to polish his image in preparation for his eventual installation as king.

Born on July 28, 1952, the prince was accorded the kind of smothering attention one would expect from growing up in a palace – in later life he told an interviewer that even at the age of 12 he was unable to tie his own shoes because courtiers had always done it for him.

“My parents tried to raise me normally but around us there were too many people trying to gain favour,” he told Dichan.

Efforts to prepare the prince for the throne began in earnest in his early teens. He was commissioned as an officer in the three branches of Thailand’s armed forces and by age 14 was sent to boarding school in England. He continued his studies at a school in Sydney in preparation for Australia’s Royal Military College at Duntroon, which he entered in 1972 and graduated from in 1975, shortly after Thailand’s neighbours Cambodia, Laos and South Vietnam fell to communist forces.

The prince took part in some military actions against Thailand’s home-grown communist insurgency, but began facing greater challenges on the personal front. In 1977, reportedly bowing to his mother’s wishes, he married a maternal first cousin, Soamsawali Kitiyakara. Their daughter was born in 1978, even as the marriage was falling apart.

His second marriage was to a commoner, Yuvadhida Polpraserth, with whom he had a daughter and four sons. After they were divorced, the prince disowned the four sons but took custody of his daughter, who is now a fashion designer.

Queen Sirikit noted the prince’s reputation with women, telling reporters when she travelled to the US in 1982: “My son the crown prince is a little bit of a Don Juan. He is a good student, a good boy, but women find him interesting and he finds women even more interesting.”

Palace elders tried to encourage Vajiralongkorn’s enthusiasm for military duties with training stints abroad. A 1980 course of advanced military training in the US whetted his appetite for flying, a passion carried on to this day. He takes a large entourage on his frequent trips to Europe on two Boeing 737s reserved for his personal use.

In 1992, he said rumours about him were “upsetting”, especially because he felt unable to defend himself because of his royal position.

Speaking to reporters specially invited to his residence, he denied some long-standing rumours: that he owned nightclubs and discotheques that were profiting by flouting legal closing hours because of links to him, that he was a godfather of various financial scams, that he rigged the national lottery.

“The money I spend is acquired honestly. I don’t want to touch money earned illegally and through the suffering of others,” he told them.

Over time, some of the more outrageous allegations have faded. But the rumour mill has continued to feed on his personal life.

In 2001, he married another commoner, Srirasmi Koet-amphaeng, with whom he had a son, Prince Dipangkorn Rasmijoti, in 2005.

Srirasmi also fell out of favour. Some of her close relatives were arrested in November 2014 on charges of abusing the crown prince’s name in collusion with corrupt police to run a massive extortion scheme. She was stripped of her royal title and the couple divorced.