It has become one of the most talked about royal spectacles for decades.

Oprah Winfrey has promised shocking content with no subject off limits and even the Queen has not been given an advance copy.

As the world waits to see what the Duke and Duchess of Sussex will reveal in their televised two-hour tell-all primetime show, here is what to look out for and what questions need answering in the continuing soap opera saga of Harry and Meghan.

– The Queen and other members of the royal family

The crunch point of the interview will be whether the couple specifically mention or criticise the monarch or other members of the royal family.

Any fault-finding with one royal will be taken as an attack on the Windsors as a whole.

Harry is known to have a good relationship with his grandmother and is unlikely to want to disrespect her, but the royal family and their aides will be waiting to see how they come across when the Sussexes spill the beans about behind the scenes royal life.

Whether the Prince of Wales or even Harry’s stepmother the Duchess of Cornwall feature will also be crucial, particularly as the duke is set to refer to his late mother Diana, Princess of Wales.

– The Duke and Duchess of CambridgeHarry and William’s bond was once so close that any divide would have seemed unthinkable.

But their rift stretches back to before the wedding when Harry was angered by what he perceived as his brother’s “snobbish” attitude to Meghan, after William questioned whether he should rush into things with the ex-Suits star.

Kate has also faced accusations she did little to bridge the divide and never really got to know Meghan, and that she snubbed her at the Sussexes’ final public royal engagement on Commonwealth Day.

Any criticism of Kate would be expected to do irreparable damage to Harry’s relationship with William.

– What does Meghan mean when she says The Firm?

The duchess has already accused “The Firm” – as the royal family is sometimes known – of “perpetuating falsehoods” about her and Harry in a clip.

But does she mean those that work behind the scenes in the establishment or the royals themselves?

In her engagement interview in 2017, Meghan said “The family has been great” and “we’ve just had a really nice time getting to know them and progressively helping me feel a part of, not just the institution, but also part of the family which has been really special”.

– And what were the “falsehoods”?

Stories surrounding Meghan included suggestions she made Kate cry after Princess Charlotte’s bridesmaid dress fitting and that Harry shouted “What Meghan wants, Meghan gets” at the Queen’s personal dresser and trusted confidante Angela Kelly in a row over a wedding tiara.

What exactly are the so-called lies according to Meghan, and who is accused of spreading them?

– What did Meghan not understand about life as a working royal and what were the main triggers for Megxit?

The duchess was warned what it was like to be a member of the royal family by Harry himself before they married.

He said in their engagement interview that he “had to have some pretty frank conversations with her to say, you know what you’re letting yourself in for, is… it’s a big deal and it’s not… it’s not easy for anybody”.

In clips of Winfrey’s programme, Meghan has criticised the constraints she faced and described the royal family as a “construct” which was different to “what people imagine”.

– The press and social media

The couple has long had an acrimonious relationship with the media and spoken of their struggles with the intense interest.

They will be expected to be highly critical of the actions of the press.

Meghan has also described herself as the most trolled person in the entire world, and said she faced “almost unsurvivable” online abuse.The duchess is the first mixed race person in modern history to marry a senior British royal and the interview may also explore any experiences of racism.

– Thomas Markle

Winfrey has said everything is up for discussion, so will this include Meghan’s estrangement from her father?

Thomas Markle has met neither Harry nor the Sussexes’ son Archie Mountbatten-Windsor.

The duchess has been estranged from her father since the time of her wedding, when he was caught staging paparazzi photographs, had a heart attack and missed walking her down the aisle.

– Family life

Harry and Meghan are expecting their second child after a miscarriage last year.

They might also discuss family life with Archie – royal fans will be hoping he makes a surprise appearance – plus their plans for their Archewell foundation.

– Allegations of bullying against Meghan

Reports circulated over the years that the duchess was difficult to work with amid stories of staff leaving and in tears.

But the interview was filmed before The Times revealed that a senior aide raised concerns over bullying and that Meghan allegedly drove out two personal assistants and humiliated another, which the duchess denies.

– The parallels

Diana’s Panorama television interview from 1995 shocked the nation when she admitted adultery, discussed Charles’ infidelity and questioned his suitability as king.

There was no going back afterwards, and divorce beckoned.

Commentators will be ready to judge whether Harry and Meghan’s sit down has the same explosive impact as Diana’s.

– Will there be any self reflection?

Will Harry and Meghan concede they could have acted differently during the troubled times facing the monarchy?

– Will there be any winners?

Harry and Meghan – depending on how audiences respond on different sides of the Atlantic – may end up garnering more public sympathy, and a greater profile in the US, and the interview is a huge scoop and financial win for Winfrey.

But royal author Penny Junor said: “It’s just such a mess. I don’t think there are going to be any winners in it.”