Did a diamond necklace end the French monarchy? The Mail's Robert Hardman and historian Kate Williams explore the downfall of Marie Antoinette and Louis XVI in new podcast

It was the scandal that rocked France and permanently damaged the reputation of Marie Antoinette.

But did the so-called 'Affair of the Diamond Necklace' really bring down the queen consort and her husband, King Louis XVI, and trigger the French Revolution? 

That is the question explored in the fourth episode of new Daily Mail podcast Queens, Kings and Dastardly Things.

Mail columnist and royal biographer Robert Hardman and his co-host, historian Kate Williams, delve into Marie-Antoinette's stunning extravagance and the chain of events that saw her lose her head at the guillotine in 1793. 

They reveal the scandalous sale of a necklace - then the most expensive in the world - that the ailing King Louis XV had commissioned for his mistress.

Marie Antoinette was inextricably caught up in the public outcry that followed, but Professor Williams and Mr Hardman reveal how all was not as it seemed.

Listen to the latest episode now: 

Marie Antoinette was the daughter of Francis I, the Holy Roman Emperor. 

He betrothed her to King Louis XVI to strengthen ties between France and Austria, her native country. 

Marie Antoinette was only 14 and Louis just 15 when they married and received two million francs worth of jewellery from her French father-in-law.

The queen would also receive many more jewels from her husband over the years of their marriage.

The glittering pieces were fitting for a woman who many regard as the first celebrity, someone who easily outshone her rather drab husband. 

It was said that her smile had an 'enchantment' that could win over 'the most brutal of her enemies'.

Her jewellery collection was by far the biggest of any French queen and rivalled only by Empress Josephine, the wife of Napoleon Bonaparte. 

By the end of 1776, Marie Antoinette had a dress allowance of 150,000 livres, at a time when the price of an an average house in a French town was 200 livres. 

As she gambled, partied and lavished money on whatever took her fancy, she racked up bills of nearly 500,000 livres. 

Versailles was the centre of fashion at its peak of eccentricity. Wigs were packed with powder and adorned with ribbons, feathers, flowers, fruit and even stuffed birds.

The queen had a personal coiffeur who designed her own 4ft tall hair-do that boasted a replica of the French warship La Belle Poule, complete with four masts, sails and jewelled portholes.   

Marie Antoinette's biggest passion was her jewels.

Louis raided the French crown jewels to allow his queen to indulge her passion for rubies, and she was also a particular fan of pearls.

As she was being painted while decked out in strands of pearls and other glittering pieces, the French economy was in the doldrums.

Harvests failed, peasants starved and rumours about the queen swirled. 

They focused not only on her remarkable excesses, but also her serial infidelity.

But it was the necklace affair in 1785 that many scholars believe paved the way for her execution.

The necklace, which was made of 647 stones weighing nearly 2,800 carats, was the most expensive in the world, valued at around $20million today. 

It had been designed by Louis XV's jewellers, the esteemed Boehmer and Bassange, for his mistress, Madame du Barry.

However, Louis passed away before the piece could be finished and so Boehmer and Bassange tried to sell the necklace to Marie Antoinette and the new King Louis VI. 

But the royal couple refused to buy it and the queen instead urged Boehmer to break it up and sell it in several pieces.

In stepped impoverished aristocrat Jeanne de Valois-Saint-Rémy, who had become the mistress of the powerful Cardinal de Rohan, a former French ambassador to Vienna.

He was keen to get back in the queen's good books after she recalled him from his post in the belief that he was stirring up trouble with her mother. 

The cardinal was encouraged by de Valois-Saint-Rémy to write to the queen.

What he did not know was that the queen's affectionate replies were being written by de Valois-Saint-Rémy. 

Believing that Marie Antoinette was in love with him, the cardinal was persuaded to meet with a woman he was told was the queen. 

In fact, this woman was a prostitute who had been hired by de Valois-Saint-Rémy to pretend to be the queen.

When the cardinal received a purported letter from the queen asking him to organise the purchase of the diamond necklace for her, he went about doing so.

After showing Boehmer and Bassange the correspondence as proof and giving them a deposit, the Cardinal was given the necklace in the belief he would deliver it to the queen.

But instead he gave it to de Valois-Saint-Rémy, who promised that she would give it to Marie-Antoinette. 

The mistress then sold its constituent jewels on the black market.

When Boehmer sought payment from the queen, she truthfully insisted that she knew nothing. 

Despite her innocence in this particular scandal, in the eyes of the public Marie Antoinette was guilty.

Here, many believed, was evidence of wrongdoing and yet more unjustifiable extravagance. 

When she visited Paris soon after giving birth to her fourth child, Marie Antoinette was greeted in 'perfect cold silence' by the crowd. 

She was also nicknamed 'Madame Deficit' and was claimed to be a heavy drinker, a lesbian and sexually voracious. 

Even Napoleon would later say: 'The queen's death must be dated from the Diamond Necklace trial.' 

Marie Antoinette and her husband were captured when they tried to flee Paris in June 1791. 

That was two years after the storming of the Bastille and the stand-off between the royal family and starving citizens in the courtyard of Versailles.

It was there that, according to legend, Marie Antoinette said, 'let them eat cake'. She did not actually say the words, but the myth has endured. 

Nine months after her husband's execution, Marie Antoinette was tried and found guilty on exaggerated charges that included high treason, promiscuity and incest with her son. 

On October 16, 1793, her head was cut off and presented to the cheering crowd.

So did the Affair of the Diamond Necklace trigger the downfall of the French monarchy?

Listen to the latest episode of Queens, Kings and Dastardly Things now wherever you get your podcasts to hear the expert verdict of Professor Williams and Mr Hardman.

Robert Hardman is the author of books including Queen of Our Times: The Life of Elizabeth II and Charles III: New King. New Court. The Inside Story. 

Professor Kate Williams is the author of the recent book The Royal Palaces: Secrets and Scandals, along with many other works.