With the funeral of late king Bhumibol Adulyadej underway, his untested and unpredictable heir has taken centre stage.

King Maha Vajiralongkorn, 65, is leading the day-long ceremony on Thursday that culminates in the cremation of his father, who reigned for 70 years.

Less than a year after taking the throne, the new sovereign, Rama X of the Chakri dynasty, has begun reshaping an enormously wealthy institution that sits at the head of Thai society.

Like all of Thailand's top royals, he remains shielded from scrutiny by a draconian royal defamation law that punishes insulting the monarchy with years in jail.

Here is what we know ─ and can safely say ─ about the monarch's first year on the throne.

What do Thais think of him?

It is ultimately impossible to know given the strictures of the lese majeste law, that carry up to 15 years in jail per charge.

But it is clear Vajiralongkorn has yet to draw the intense affection lavished on his father, who reached cult-figure status through a mix of propaganda, natural charisma and historical circumstance.

Thais are well-versed in rumours of the thrice-divorced heir's personal life ─ a sharp contrast to Bhumibol's reputation for virtuousness and frugality.

Prosecutions show no sign of letting up under Vajiralongkorn, with more than a dozen people charged over the past year and the harshest sentence reaching 35 years.

The first suspect to be detained under the new king was a student activist, who shared a BBC Thai language profile of Vajiralongkorn on Facebook.

The article included details about the monarch's personal life that are widely known but never spoken of in public.

What has he done since taking power?

There are already signs that Vajiralongkorn is consolidating his control of the palace ─ and its huge wealth. In July the king was granted power to appoint all members of a body that oversees the Crown Property Bureau (CPB) ─ which administers the monarchy's multi-billion-dollar estate.

The committee was previously headed by the finance minister, an arrangement that nodded towards public accountability over a trust estimated to be worth $30-60 billion.

Months after the change, $500 million worth of CPB shares in a Thai bank were transferred on the king's behalf without explanation.

Vajiralongkorn has also taken direct control of five agencies overseeing palace affairs and security that were previously run by the government or military.

Earlier in the year he ordered the removal of constitutional provisions that required the monarch to appoint a regent when overseas or have all royal decrees countersigned by a government official.

But as with all things royal in Thailand, observers are left guessing at the real motivations behind palace moves.

How about his personal life?

Multi-lingual and a trained pilot, Vajiralongkorn, who was born on July 28, 1952, has spent significant periods of his adult life overseas.

As crown prince he shied away from the royal appearances.

When asked about the pressure of being crown prince in a rare 1979 BBC interview, Vajiralongkorn answered cryptically.

“It's difficult to say what it is like to be a fish when you are fish, or what it is like to be a bird when you are a bird,” he said in English.

“In every life I believe that there are pressures and stresses... I'm not special.” Since his father's death, Vajiralongkorn has been forefront of Buddhist rituals and funeral rites leading up to the cremation.

But he remains primarily based in Germany, where his 12-year-old son is in school, and even failed to appear for nationwide celebrations marking his birthday.

His son, Dipangkorn Rasmijoti, is from a third marriage which like the previous two ended in high-profile divorce.

Official photos show the pair enjoying an active lifestyle of biking, hiking and skiing in Europe.

But Dipangkorn's mother, former princess Srirasmi Suwadee, has not been seen in public since their bitter split three years ago.

Her family suffered a very public fall from grace ─ including jail time for her parents ─ after they were accused of profiting from their ties to the monarchy.

Similar fates have befallen other former allies of the king, who has publicly purged a number of advisers since coming to power.

Other one-time close advisers, including a famous soothsayer, have died in custody of apparent natural causes after being accused of lese majeste.