Michael Wolff's hotly anticipated book Fire and Fury will be released across the US tonight (4 January). His withering exposé on the Donald Trump White House is expected to sell millions of copies on the back of its stunning revelations about the administration's personalities and conflicts.

Many political journalists spend years attempting to get close to their chosen subjects – but for Michael Wolff it took just 18 months. How did the New York writer embed himself so deeply within Donald Trump's team?

According to Wolff himself he showed up to Trump Tower days before the president's inauguration and told him he would like to write a book about him. "A book?", was Trump's response, "I hear a lot of people want to write books."

Wolff had already laid the ground for the meeting some time before. In June 2016 Wolff wrote a largely positive interview with Trump for The Hollywood Reporter. Trump, largely distrustful of the press, was apparently extremely pleased with the resulting magazine cover and lowered his guard.

Wolff was then given a 'blue' appointment badge by the Secret Service, allowing him unrestricted White House access – an advantage not afforded to other political correspondents. This free rein surprised even Wolff, who made a couch in the West Wing his temporary 'fly on the wall' office. From this vantage point he was able to see White House personalities in daily action.

Bald and with a flamboyant dress sense, Michael Wolff is a conspicuous presence virtually everywhere he goes – yet no one attempted to remove this unimpeded access which resulted in 200 interviews with staff. This oversight has apparently surprised Wolff himself.

In a recent tweet Donald Trump denied Wolff's account of events and has said he refused to speak with the columnist during the whole period he spent working at the White House.

Wolff's resulting book Fire and Fury paints a picture of a White House in chaos, struggling to gain direction without presidential leadership. The book has already topped the Amazon book charts despite attempts by Trump's legal to stop its release.