Aussie soldier who mentored Thai king during a trip Down Under reveals what the controversial leader was like before he became a 'billionaire playboy with a harem of sex soldiers'

An Australian soldier who was chosen to mentor the future King of Thailand has spoken of his time with the royal as a 'quiet' and 'reserved' young teenager - before he became a controversial ruler with a 'harem of sex soldiers'.

King Maha Vajiralongkorn, 68, is known to his 70 million subjects for his outlandish style choices - previously bearing tiny crop tops and garish fake tattoos. 

Vajiralongkorn is also one of the world's richest monarchs with assets worth an estimated $40billion.

The king - who is on his fourth wife and has seven children - has in recent months been the target of pro-democracy protests campaigning against his palace fortune and personal control of entire army units.

A bizarre report in May claimed the monarch had booked out a floor at an Alpine hotel in Germany, where he was accompanied by 20 concubines with military ranks. 

But one of Vajiralongkorn's fellow cadets at Canberra's elite Royal Military College said the young man gave off a very different impression when he arrived as the Thai Crown Prince at the training institution in 1972.  

Thailand's King Maha Vajiralongkorn is transported on a royal palanquin by royal bearers during the Royal Procession outside the Grand Palace in Bangkok, Thailand in December 2019

Thai pro-democracy protest leaders rallying in Bangkok on October 29. The king has in recent months been the target of pro-democracy protests campaigning against his palace fortune and personal control of entire army units

'At the time it was just so normal - there was no big deal about it. We called him "Vaji",' former Duntroon Military College student Gary Stone told 60 Minutes.

'He did everything we expected of him.  

'He was one of our section, part of our platoon and there was no special treatment for him. It was rather wonderful.'

Vajiralongkorn arrived in Australia in 1970 and studied at The King’s School in Parramatta, western Sydney before moving on to Duntroon.

Mr Stone said the public perception of the monarch is very different to how other military trainees saw him.

One of Vajiralongkorn's fellow students at Canberra's elite Royal Military College said the young man was 'quiet', 'polite' and 'reserved' when they trained together. Vajiralongkorn is pictured at the college in 1972

Pictured is government correspondence showing how Vajiralongkorn's admission to Duntroon had to be postponed a year because he had no chance of graduating high school

'Personally he's a quiet, reserved and quite polite and respectful person - that's the character we experienced there at - and I'm sure that's the way he's lived most of his life,' Mr Stone said.

Declassified correspondence detailing the monarch's six years in Australia during his early years can also now be revealed - showing how authorities Down Under and in Thailand went back and forth over the Crown Prince's education.

One 1971 letter from the Department of External Affairs told how Vajiralongkorn's admission to Duntroon had to be postponed a year because he had no chance of graduating high school, The Sydney Morning Herald reported.

Pictured: The Thai king when he was still a prince in Germany in May 2016 wearing a tank top and covered in fake tattoos being received by officials

Pictured: The Thai king right with his father and predecessor King Bhumibol in full guards' uniform in Bangkok

The memo said the Crown Prince 'should not be exposed to the embarrassment of failure in the February 1971 examinations'.

In 1973, a rumour emerged while Vajiralongkorn was at Duntroon he had been shot - hearsay the Australian embassy put down to an attempt to discredit the Thai rulers.

Vajiralongkorn as a child. Declassified correspondence detailing the now-monarch's six years in Australia

The young royal also spent time with the Special Air Service Regiment in Perth before moving back to Thailand in 1976.

The publication of a series of official government cables about Vajiralongkorn's time in Australia comes amid massive protests against his rule in Thailand.

The Thai palace has made no official comment on protests that began by seeking the departure of Prime Minister Prayuth Chan-ocha before breaking a longstanding taboo by calling for curbs on the king's powers. 

Protesters criticise the king's long stays in Germany as wasteful and accuse the monarchy of enabling decades of army domination by accepting coups such as the one in which Chan-ocha took power in 2014.  

The biggest protests have drawn tens of thousands of people. There was no official estimate for crowds earlier this month.

Reuters journalists estimated the number at more than 10,000.

Royalist leader Warong Dechgitvigrom, who has been trying to rally people to counter the protesters, said the king had told him to 'help get the truth out'.

A Royal Household Bureau handout photo shows Thai King Maha Vajiralongkorn wearing a crown during the coronation ceremony at the Grand Palace in Bangkok, Thailand, 04 May 2019

Prayuth's government banned protests last month and arrested many of the best known leaders, but the emergency measures were cancelled after they backfired by drawing many more people onto Bangkok streets.

Public criticism of the king or his family is illegal, with insults to the monarchy punishable by up to 15 years in prison under Thailand’s strict 'lese majeste' laws. 

A report by Bild in May found Vajiralongkorn and his entourage had booked out the whole fourth floor of a four-star retreat in southern Germany - which includes a 'pleasure room' and is decked out with 'treasures and antiques' from Thailand. 

His 'sex soldiers' were said to be assembled as a military unit called the SAS like Britain's special forces - with the same motto, 'who dares wins'. 

The Grand Hotel Sonnenbichl where the king was said to be staying is in Garmisch-Partenkirchen, a ski town near the Austrian border which saw most tourists stay away.

The hotel's website said it was at the time 'currently unavailable for bookings' because of the coronavirus pandemic, without mentioning its long-term guests.

Thailand's King Maha Vajiralongkorn and Queen Suthida during their wedding ceremony in Bangkok in May last year. According to tradition, the King has a semi-divine status and must be seated higher than those around him 

In 2001, the king wed his third wife Srirasmi Suwadee, describing her as a 'modest and patient' woman who 'never says bad things towards anyone'. 

In 2007, footage published online showed the couple throwing a party for his pet poodle - who held the rank of Air Chief Marshall - at the Royal Palace in Bangkok.

Princess Srirasmi, a former waitress, sang happy birthday to the dog topless.

The couple had a son but the marriage collapsed at the end of 2014.

Prince Maha stripped her of her royal titles and, after granting her a reported £4.5m settlement, exiled her to an undisclosed location in Thailand.

The Grand Hotel Sonnenbichl in southern Germany where the King of Thailand was staying during the lockdown while other guests were reportedly kept out because of the pandemic