One thing of which Lady Worsley could never have been accused was leading a boring life.

With a rumoured 27 lovers to her name, she blazed a scandalous trail through 18th century society.

Within years of her marriage at the Harewood estate in 1775, she had set off on a course of self-destruction which would see her hauled before the courts, banished to the Continent and caught up in the French Revolution.

She would be forbidden contact with her son, and it is alleged that her young daughter – fathered by a lover – was murdered by her husband.

Another child would go on to blackmail her and she would end her life the wife of a fortune hunter.

As the author of a newly published book about her says: “You couldn’t make it up.”

Known to many only as the figure in a well known Joshua Reynolds painting, Seymour Dorothy Fleming was the stepdaughter of Edwin Lascelles, the first Earl of Harewood, and lived at Harewood House from 1771-1775, where she began to develop a reputation for unruly behaviour.

One of the inspirations for Richard Brinsley Sheridan’s play School for Scandal, she gained notoriety when she was at the centre of a court case as her aggrieved husband attempted to sue her lover for an astronomical £20,000 in damages.

In the course of the proceedings, the Worsleys’ scandalous sexual arrangements, voyeuristic tendencies and bed-hopping antics were laid bare, giving the satirists of the day plenty of material.

And her life was to be dogged by scandal, intrigue and drama for many years to follow.

Historical consultant and former Leeds student Hallie Rubenhold became intrigued by the scarlet-clad woman in the Reynolds painting, Lady Worsley and, after three years of research, she has launched Lady Worsley’s Whim.

And she will be talking about her scandalous subject in an event at Harewood House this weekend.

Hallie, who studied the history of art during her time at Leeds, said she was aware of the portrait of Lady Worsley.

“It is such an iconic portrait – you come across it in a number of books, and I went to see it at Harewood,” she said.

She decided to do some digging into the topic which she describes as “beyond interesting.” She said: “The story just kept getting weirder. As I was writing it, I thought, you couldn’t make this up – people wouldn’t believe it. Sometimes real life is stranger than fiction.”

It took her about three years to research and write the book. It was a very long endeavour and very painful to write.

“The thing about writing fact is that you just can’t make it up. If the evidence isn’t there you can’t present it as though it happened.”

“As I was doing this research, my sympathies went from Sir Richard to Lady Worsley and back again. And at various times I felt sympathy and disgust for both of them.”

She said the notion that the upper echelons of 18th century society behaved as we do now was simply untrue.

“Actually, they were not like us at all,” said Hallie. “We would have hated them and they would have looked down their noses at us.

“This wasn’t our world, it was their world, and they were both very unpleasant people.”

She said while Richard Worsley was a very damaged man, Lady Worsley was probably mentally unstable.

“Some of things she did would have been outrageous even today,” she said.

One incident which caused consternation in the area around Harewood was when she went off on a three-day “bender” and, along with two female friends, attempted to burn down a local inn.

They tried to put out the flames with their own urine and then began emptying chamber pots on to the heads of passers by.

The shocking incident was the subject of numerous letters in circulation in the area.

But it was through an infamous court case that Lady Worsley found national notoriety.

After the subsequent divorce she was forced to go abroad, and probably never saw her young son again.

She was also parted from her baby daughter, despite the fact that the child was fathered by her lover.

“It is very tragic what happened with her children,” Hallie said. “But she would have known this when she ran off.”

“She probably never saw her son again. Her daughter died, and it was suspected at the time that she was murdered by Worsley.”

While the number of Lady Worsley’s lovers may have been exaggerated – the real figure could have been more like five – society was shocked by her unrepentant behaviour, according to freelance researcher Karen Lynch. Karen used to work at Harewood and had been fascinated by the tales she heard about Lady Worsley.

When she found out that Hallie was writing the book, she met her and shared her knowledge.

Karen, who lives in Ilkley, said: “With lots of stories you get misinformation and they become embellished and are often based on no fact whatsoever.

“I was always eager to find out whether she really was a bad girl or whether the stories had been blown out of proportion. But when you start to investigate, she was actually worse.”

She added: “Everybody will compare this with Georgiana, of course. Her affairs were well-known but she didn’t flaunt it, whereas Lady Worsley did flaunt it.”

“When the adultery case was coming to court, instead of hushing it up she insisted on more men coming to court – and even got a doctor in to say that she got venereal disease.”

The public just couldn’t get enough of the scandal, and when transcripts of the case went on sale they were snapped up.

“It went to six or seven editions and sold like hot cakes,” she said. “It was an absolute best seller.”

She said she had enjoyed discussing her own research with Hallie.

“We have had long conversation talking things through on the phone and we met occasionally for a non-stop gossip – as we are probably the only two Lady Worsley obsessives in Britain.”

She stressed that Hallie’s book had been warmly received so far with extremely good reviews.

“Hallie must be over the moon,” she said.