When Donald Trump bought the Mar-a-Lago estate in 1985, the snooty old-money locals reacted as if he had beaten a fine old lady to death – and in a manner of speaking, that’s precisely what he’d done.

The way he conducted the deal was all but extortion and now almost legend.

The 126-room mansion gained new infamy after the president used the venue to host an 800-person gathering at the weekend, without whispering a word to the press corps that monitors his every move.

Mar-a-Lago was built in the 1920s by cereal heiress Marjorie Merriweather Post, and was regarded as the jewel of the Palm Beach neighbourhood that was also home to the Kennedys, Fords and Du Ponts.

When Post died in 1973, she bequeathed the 20-acre estate to the US government, to be used as the official winter White House.

But neither Richard Nixon nor Jimmy Carter took up the offer. In 1980, Carter returned the mansion to the Post Trust – because it was costing the government $1 million a year in maintenance and taxes.

Post’s daughters put the place on the market for $20 million. Mar-a-Lago might have inspired much nostalgia in Palm Beach, but no one actually wanted to buy it. It was falling into disrepair.

Trump claims a chauffeur told him about the place and went to check it out. He offered the sisters a reported $28 million for the house and antique furnishings. They held out for more cash, but the market turned.

And then Trump pulled a knife: he told the sisters he’d bought the beachfront property immediately in front of Mar-a-Lago and threatened to build the ugliest house in the world. They caved and accepted $8 million for the lot.

Ten years later, after refurbishing the joint with gold sinks and $7 million worth of gold leaf, he opened Mar-a-Lago as a private club.

Donald Trump emerges from Air Force One in West Palm Beach. Photo: Getty

Today, Mar-a-Lago is Trump’s revenge on the old-money families who loathed his coming to Palm Beach. It’s where he can relax and act like a king instead of just a president, no matter who calls him a vulgarian.

People pay a fortune here to line up and kiss his ring.

As of November last year, people paid a $100,000 initiation fee to join Trump’s private clubhouse.

Since he became US President, the initiation fee controversially doubled to $200,000 – because the ear of the leader of the free world is much more valuable than that of a reality TV star.

It gets doubly murky because Mar-a-Lago is Trump’s winter White House, where he likes to do government business on weekends. Other presidents had winter White Houses. Barack Obama had a rental place in Hawaii. But none of them ran their retreats as a private club for money.

Nor did they conduct national security business in full view of club members – as reportedly occurred last weekend when Trump hosted Japanese Prime Minister Shinzo Abe and North Korea crashed the party by test-launching a ballistic missile into Abe’s backyard.

Paying member of Mar-A-Lago takes photo of Trump advisers using cell phone flashlights to inspect apparently classified docs with Abe: pic.twitter.com/BNZJnjAuOw

— Natasha Bertrand (@NatashaBertrand) February 13, 2017

Photographs posted on social media by club members showed Trump and his aides studying what were possible classified documents and making high-level calls to Washington.

Mar-a-Lago is one of the many unprecedented and ethics-challenging aspects of a presidency that offers surprises almost daily – with events happening so fast that there just seems no time at all to hold anyone to account.

What else might be going on?

Mar-a-Lago isn’t Trump’s only clubhouse. In November, two weeks after winning the election, he was recorded inviting wealthy members of his Bedminster golf club in New Jersey to watch him interview candidates – potential “generals and dictators” – for posts in his administration.

He said it would be “fun”.

It certainly looked fun. There were pictures of club members posing with the army officer carrying the “nuclear football” – the device from which Trump launches nuclear bombs.