The truth behind Charles and Camilla's affair storyline in The Crown

As Charles and Diana's marriage runs further and further into difficulty, we see Charles and Camilla's affair develop with furtive phone calls and illicit meetings and declarations of love.

If you're wondering how season four is going down with critics, check out RadioTimes.com's The Crown review.

Here's what we know about the truth behind what we see on screen.

Why didn't Charles marry Camilla?

As we saw in season three, Prince Charles (Josh O'Connor) had a passionate romance with Camilla Shand (Emerald Fennell) as part of a complicated love quadrangle with Charles, Anne, Andrew and Camilla – but it never got a chance to turn into a royal marriage.

That came down to a combination of: a) meddling from the Royal Family, b) Camilla's own strong feelings for her soon-to-be-husband Andrew Parker Bowles (played by Andrew Buchan), and c) Charles failing to seize the day.

But that, of course, was not the end of the Charles and Camilla story. Not by a long stretch.

Did Charles continue his affair during his engagement to Diana?

After Diana emerged as a potential bride for Charles in mid-1980, they had a very speedy courtship – culminating in the announcement of their engagement in February 1981, and the moment Charles answered a reporter's question about his love for his new fiancée with the memorable phrase: "Whatever 'in love' means." The wedding date was set for just five months later.

Camilla had married Andrew Parker Bowles in 1973, giving birth to Tom in 1974 and Laura in 1978. Publicly, Charles and Camilla remained close friends, and they spent plenty of time together. According to History Extra, the two of them resumed their affair in the late seventies.

It's not clear to what extent their relationship was physical, or if it continued to be physical during Charles and Diana's courtship and engagement. But just as we see in The Crown, Camilla never left Charles's life or stopped being his confidante.

Did Camilla and Diana go for lunch before the marriage?

It seems so! After the engagement, Diana was moved from the home she shared with her flatmates to the Queen Mother's residence at Clarence House, where she was left to her own devices. When she was shown to her bedroom by a servant, there was a letter lying on her bed from Camilla Parker Bowles - inviting her to lunch.

Based on interviews with Diana, Andrew Morton writes in his book: "It was during that meeting, arranged to coincide with Prince Charles's trip to Australia and New Zealand, that Diana became suspicious."

Camilla apparently asked if Diana was planning to go hunting with her new husband, and was relieved to hear that she wasn't. "Diana later realised that Camilla saw Charles's love of hunting as a conduit to maintaining her own friendship."

Is the 'Fred and Gladys' bracelet storyline true?

Watching events unfold in The Crown, you'd be forgiven for thinking that the storyline about the bracelet must surely be a work of fiction. Poor Diana, discovering during her engagement that her (absent) fiancé had commissioned a special engraved bracelet for his supposedly-ex girlfriend!

But this actually appears to be true, according to Diana's own account (and according to Charles's own biographer). Just as we saw in The Crown, the discovery of the bracelet made her consider doing the impossible – calling the whole thing off.

In her biography of Prince Charles, Catherine Mayer writes: "Behind the scenes, both bride and bridegroom grappled with swirling anxieties and separately persuaded themselves that to bolt would prove more damaging than to continue the pageant. Curled venomously amongst a pile of wedding presents and cards, Diana had discovered a bracelet bearing the initials 'GF', intended for Camilla."

Morton's version of events differs slightly: in his telling, a parcel arrived at Buckingham Palace which Diana insisted on opening, "despite firm remonstrations from the Prince's righthand man" – and inside she discovered the bracelet with the G and F initials. Morton says she actually confronted Charles straight away, but "in spite of her angry and tearful protests" Charles insisted on giving the gift to Camilla anyway when he visited her alone on the Monday before the wedding.

Princess Diana later told Morton that the initials stood for 'Gladys' and 'Fred', Camilla and Charles's pet names for one another, which she'd gleaned from a note on a bouquet of flowers and from Charles's own friends.

For his part, Jonathan Dimbleby (Charles's biographer) claims that the initials stood for 'Girl Friday', the Princes's nickname for Camilla. Either version spelled bad news for Diana's upcoming marriage.

After finding the bracelet, Diana had lunch with her sisters and informed them that she couldn't marry Charles. According to her, they responded: "Bad luck... your face is on the tea towels so you're too late to chicken out."

Two days before the wedding, at a rehearsal at St Paul's Cathedral, she broke down and wept.

Did Charles ever stop his affair with Camilla?

That's the big question, and the answer is disputed.

Camilla clearly remained Prince Charles's sounding board, and his main source of advice. She was the person he turned to for advice on whether he should go ahead with his wedding, and advice about his marital problems, although the extent of their contact may have waxed and waned.

Diana came to believe that Charles was still seeing Camilla. Biographers Anthony Holden and James Whitaker have placed the date in 1983 or before, with one frequently-cited story that in November of that year Diana pressed the redial button in Charles's study and it connected to Camilla. She also noticed unexplained absences and phone calls.

She captured all of this with the memorable phrase: "There were three of us in this this marriage so it was a bit crowded."

Meanwhile, Charles has insisted that he did not resume the affair until November 1986 after the "irretrievable" breakdown of his marriage to Diana.

In 1994, in a filmed interview, Jonathan Dimbleby asked him if he had tried to be faithful and honourable to his wife when he took on the vow of marriage."Yes, absolutely," Charles said. And was he? "Yes, until it became irretrievably broken down, us both having tried."

Charles continues to insist that this timeline is correct. Mayer writes: "This seems to him an important point – a point of honour. Despite everything that has happened, a source says he still doesn't realise that it is also semantic. Whether or not he and Camilla consummated their passion in the early years of his marriage to Diana, they never entirely relinquished it."

What happened after the affair fully resumed?

After the birth of Prince Harry in 1984, Charles and Diana's marriage became increasingly troubled, and by November 1986 at the absolute latest he had fully resumed his affair with Camilla Parker Bowles.

According to Morton, in 1989 Diana finally confronted Camilla at a party in a "brisk conversation in which Diana gave voice to her feelings about what she believed to be the nature of the friendship between Camilla and her husband."

Princess Diana also had at least one affair, beginning a relationship with Household Cavalry member (and riding instructor) Major James Hewitt.

All the painful details really became public in the '90s, in the "War of the Waleses". In 1992, Charles and Diana's formal separation was announced; that was also the year Andrew Morton published his book Diana: Her True Story, based on secret interviews.

The following year, there was the scandal known as "Camillagate", in which transcripts of secretly-recorded tapes were released of a 1989 phone call between Charles and Camilla, involving conversations regarding where and when they could meet up next to have sex. That followed hot on the heels of the "Squidgygate" scandal, based on a taped conversation between Diana and her friend James Gilbey.

In 1994, the Parker Bowles-es filed for divorce, having been living apart for some time. Meanwhile, Charles and Diana divorced in 1996. Tragically, Diana was killed in a car crash the following year.

After that, Camilla and Charles – both now divorced – continued their relationship, and finally in 2005 they became engaged and married in a civil ceremony. Charles's second wife became "Camilla, Duchess of Cornwall".

The Crown is available on Netflix now. Looking for something else to watch? Check out our guide to the best series on Netflix and best movies on Netflix, visit our TV Guide, or find out about upcoming new TV shows 2020.