According to popular legend, she was also the "Wicked Lady", a highwaywoman who terrorised the English county of Hertfordshire before dying from gunshot wounds sustained during a robbery.

The Fanshawe family were committed Royalists, and when the Civil War broke out in 1642, Simon, his new wife and stepdaughter joined King Charles I in Oxford, his wartime capital.

The family then arranged for orphaned Katherine, heir to the Ferrers estates, to marry Thomas Fanshawe, her stepfather's nephew, when she reached a marriageable age.

Thomas Fanshawe had become involved in Booth's uprising, a Presbyterian rebellion in the north of England, and was imprisoned in the Tower of London in September 1659, although he was released in February 1660.

However, since Katherine's husband was imprisoned in 1659 following the Booth uprising in the north, and not released until February 1660, the issue then becomes one of paternity, since a pregnancy of four months duration, during those times, could not have produced a child that would have survived.

According to the popular legend, often told with an emphasis on hauntings by her ghost, Katherine came into highway robbery in her husband's absence in order to redress her fast-dwindling fortune.

During this time many highwaymen were Royalist supporters bereft of home, estates or income, who were left to make a living as best they could, so any courteous highway robber was perceived to be one of these well-mannered gentlemen.

The persistent rumour is that she was shot as a highwayman on Nomansland Common on the edge of Wheathampstead, and died of her wounds while trying to ride back to a secret staircase entry at Markyate Cell.

[3][4] Apart from robbery, a catalogue of mayhem in the area was later attributed to Katherine that included burning houses, slaughtering livestock, even killing a constable or other officer of the law.

Much of the supposed activity might be blamed on bands of brigands and the unrest relating to the Civil War, and there is no confirmation as to whether the mayhem and robberies in the area ceased with Katherine's death.

[4] The last member of the House of Lords hanged in England, the "wicked" Laurence Shirley, Earl Ferrers, was executed at Tyburn for the murder of his manservant in 1760, one hundred years after Katherine's death.

A 1945 film version called The Wicked Lady, with Margaret Lockwood in the lead role and James Mason as Ralph Chaplin's alter ego Jerry Jackson, broke all British box office records for the time.