Hogarth is said to have been inspired in his series by a real person.
The second picture shows a courtesan, who he was commissioned to draw. He apparently mused then upon her earlier and later life, which became A Harlot's Progress. There is no indication, in reality, that he followed the same woman for the rest of her life.
However, every other person in his paintings is real. For example, there really was an Elizabeth Needham, known as 'Mother' Needham, who procured girls for prostitution. She was sentenced to stand in the pillory twice.
The first time, magistrates allowed her to lie down in front of the pillory, with an armed guard around her for protection. That didn't stop the crowd pelting her with missiles though. She was effectively stoned practically to death, then died of her injuries before she could face the pillory for a second time.
Her image was widely circulated at the time and Hogarth blatantly placed her, in her role, in the first scene in A Harlot's Progress. He was painting that series in the same year as 'Mother' Needham was killed.
Hogarth called his 'harlot' Moll Hackabout. Moll is both short for Mary and a colloquial term for a prostitute. But it also recalled one of the best-selling novels of the time, Moll Flanders by Daniel Defoe. The heroine of that book also got by on her womanly charms.
The surname used would have been equally recognizable by 18th century society. Kate Hackabout was a prostitute, whose brothel was broken up by Sir John Gonson in August 1730. He is the magistrate depicted doing exactly the same to Moll's disorderly house in the third painting.
Kate was arrested in reality and consigned to jail. Her brother Francis Hackabout was hanged at Tyburn, as a highwayman, in the same year. All of this was recent news, when Hogarth was painting A Harlot's Progress.
There was no real Mary Collins, but there was Kate Hackabout. Could she have been his muse as shown in this movie?