Roy Marcus Cohn had been Joseph McCarthy‘s legal henchman and attack dog. He had prosecuted Ethel and Julius Rosenberg, the atom bomb spies, and other suspected communists with only the slimmest of evidence. Cohn was generally seen as a man who would stop at nothing to win a case (including entrapment, harassment, and bribing witnesses). British humourist and broadcaster Ned Sherrin once recalled interviewing Cohn in 1978 over breakfast during which the lawyer turned to an aide and, within Sherrin’s earshot, said: ‘Did you mail that cheque to the judge?’

As brilliant as he was arrogant, Cohn soon rose to become special assistant to the US attorney general and became a protégé of J Edgar Hoover, head of the FBI. He was first hailed a ‘boy wonder’, later a ‘legal executioner’.

Towards the end of his career Cohn became a mentor to a young businessman called Donald Trump and Cohn is the fulcrum in Tony Kushner’s 1993 play Angels in America which will be revived by the National Theatre in London’s West End this May (previews from 11 April) with Nathan Lane playing Cohn. The revival celebrates the play’s 25th anniversary.

Set in 1985, this cultural blockbuster said that America had reached crisis point. The grinning, pompadoured Ronald Reagan was in the White House, Aids was threatening to decimate the population, and on Wall Street it was official: Greed is Good. It was the End Times. Some 25 years after its premiere at the Eureka Theatre in San Francisco, Angels in America returns producing much excitement in its wake. Its sweeping plot of corruption in high places, of belligerent politicos with no morals, of an apocalyptic vision of America’s fractured idealism seems to be very much of the moment. Back in the 1990s the play had a triumphant showing in Los Angeles before hitting Broadway and there followed a star-studded, multi-award-winning HBO miniseries.

Not that there was much that was mini about it. The play comes in two sections (London will see both). It’s a production of Big Themes – part metaphysical, part metaphorical, part mystical. The plot is baroque. The New York Times critic called it a ‘vast, miraculous play’. But Kushner’s subtitle sums it up best: ‘A Gay Fantasia of National Themes’. In one scene Roy Cohn’s African-American male nurse (who moonlights as a drag queen) says ‘I hate America. I hate this country. I hate the lies it tells itself about union when I don’t see any union, about democracy when all I see is democracy dying; and justice and the pursuit of happiness, I hate how America has bartered those things’. How relevant does this sound years after it was written – years that have seen the banking crisis, Fannie Mae, 9/11, Sarah Palin, ‘Dubya’, Rodney King, equal marriage, Obamacare, post-communism, a near-cure for Aids, Daesh/Isis, alt-right, fake news, alternative truth and the kingdom of Twitter? Now Angels in America’s message of catharsis seems more urgent than ever.

At the centre of the play’s whirlwind stands Roy Cohn. A figure who certainly has all the best lines. The Cohn character – an anti-Semitic homophobe, who is also a gay Jew, was described by the original producer of the play, Gordon Davidson, as ‘half Falstaff, half Iago’. Cohn, with the Trump connection, remains a villain for our times. ‘The bold-faced lies, guilt-free immorality, blithe refusal of introspection, and astonishing vulgarity that we now associate with the 45th president are key elements of a style created by Cohn,’ writes Oskar Eustis, Angels in America’s one-time co-director, blisteringly in April’s Vanity Fair.  In the 2003 TV miniseries Al Pacino powerfully played Cohn, giving the character the very essence of irredeemable evil. Although he saw himself as a maverick, standing against long-established, respectable law firms and winning against the odds, Cohn went on to become a power broker and Mr Fixit for an array of high-profile and fashionable clients.

One story that illustrates the Cohn saga better than most involves Alan Jay Lerner, the famed American lyricist of such hit musicals as Camelot, Gigi, and every true Scot’s favourite, Brigadoon, but he received a different kind of fame in the mid-1960s during his divorce trial from hell.

Like many theatre folk Lerner was superstitious. He always avoided the number 13 until he met his fourth wife, two of whose initials were ‘M’, the thirteenth letter of the alphabet. ‘Never fuck a lawyer,’ one of Lerner’s friends counselled. But it was too late. Lerner had fallen for Corsican-born Micheline Muselli Pozzo di Borgo, the youngest avocat ever called to the French Bar.

In 1965, at the height of Lerner’s fame – his classic stage musical My Fair Lady had just been made into a movie with Audrey Hepburn – he was involved in the messiest divorce scandals since the marathon proceedings between the Duke and Duchess of Argyll at the Edinburgh Court of Session two years earlier.

Perhaps Lerner’s most enigmatic production with his longtime collaborator Fritz Loewe was Camelot, based on the King Arthur legend. Dedicated to Micheline, the 1960 Broadway hit starred Richard Burton and Julie Andrews and told of ‘one brief shining moment that was known as Camelot’. The musical gave its name to the similarly brief JFK administration.

Like Camelot, Lerner’s fourth marriage was brought to a sad end too. The lyricist married Micheline in 1957 and by most accounts she was a tough cookie. Not for nothing had she made her name in Paris legal circles as a formidable criminal lawyer who prided herself on never losing a case. Clearly she was not the sort of person to tangle with in court, something her husband was soon to discover.

Success had not been altogether kind to the Oscar-winning librettist who had acquired an addiction to amphetamines which was said to be partly responsible for his turbulent marriage to Micheline, the fate of which was sealed in 1964 when she filed for a separation claiming ‘marital cruelty’.

Micheline engaged Roy Cohn. Like Micheline, Cohn had an early, precocious talent, being admitted to the New York Bar at the age of 21. Cohn was hired to impugn Lerner’s character. ‘It is ironic [that] Roy Cohn used an imputation of homosexuality to smear Lerner. After his death of Aids (in 1986) it was revealed that Cohn had been an active homosexual,’ observes Gene Lees, Lerner’s biographer.

In court, after the slippery Cohn played on Mr Lerner’s success and status he won for Mrs L the largest alimony payment in the history of New York State. Throughout his life the divorce courts became accustomed to Alan J Lerner’s face, but the trial between Alan and Micheline dogged the composer for years after the decree absolute. Up until he died Micheline sought thousands of dollars in alimony arrears.

Lerner’s career never again scaled the heights of his My Fair Lady success. His musical on the life of Coco Chanel was a particular flop. Lerner once said: ‘The female sex has no greater fan than I, and I have the bills to prove it.’

Cohn was thrice tried and acquitted on federal charges of conspiracy, bribery, and fraud, but was finally disbarred only two months before his death. Incredibly, all these years later the devilish Roy M Cohn lives on in his equally demonic pupil Donald J Trump. What the world needs now is, quite simply, divine intervention.

There are a number of live and encore cinema screenings of the National Theatre’s Angels in America across Scotland. See the National Theatre website for more.