Although Charles Dickens would likely have been a man of the cinema had he lived in a later age, he would have blanched at the prospect of “The Invisible Woman,” which went into production in the UK this week. The second film directed by Ralph Fiennes, it’s a drama based on Claire Tomalin’s speculative 1990 biography of Ellen (“Nelly”) Ternan, who for 13 years was Dickens’s mistress. Fiennes is playing Dickens and Felicity Jones (“Like Crazy”) has the plum part of Nelly.

Kristin Scott Thomas, acting with Fiennes for the first time since “The English Patient,” has been cast as Frances Ternan, a respected actress and a more successful one than Nelly or her sisters Fanny and Maria. (Fanny would marry Thomas Trollope, a prolific writer overshadowed by his more famous brother Anthony.) Tom Hollander is playing the novelist Wilkie Collins, one of Dickens’ closest friends.

Dickens’s affair with Ternan, who was 27 years his junior, was conducted in great secrecy because of Victorian mores concerning adultery and the novelist’s need to preserve an unblemished reputation. They met in 1857, when Nelly was 18 and Dickens was already emotionally estranged from his wife Catherine, and he became the financial patron of the family, which had lost its patriarch in 1846.

Although there is no written evidence, Tomalin makes a convincing case in her recent Dickens biography that he made Nelly pregnant in 1862 or 1863, which is why she disappeared, probably to France. Dickens, who agonized over the affair and came close to a breakdown, visited France frequently between 1863 and 1865. The child is believed to have been a boy – Dickens’s eighth son – and to have died young.

On June 9, 1865, Dickens, Nelly, and Mrs. Ternan were traveling together on a “tidal train” to Charing Cross in London that struck a bridge and fell into the river at Staplehurst, in Kent.  The first-class carriage in which they were sitting was the only one not to plunge into the water. Nelly, who was injured in the neck and an arm, and her mother were spirited away lest it be discovered they had been with Dickens.

He stayed at the scene of the accident to help other passengers, while thoughtfully retrieving the manuscript of “Our Mutual Friend” from the wreckage. It was the last novel he completed. He never recovered from the trauma and died of a stroke in 1870, five years to the day of the accident.

Six years later, Nelly married George Wharton Robinson, twelve years her junior. They had a son and daughter and ran a boys’ school. She died in 1914, having never spoken publicly of her affair with Dickens.

Fiennes is doing his bit for Dickens in the novelist’s bicentenary. He also plays the convict Magwitch in Mike Newell’s upcoming film of “Great Expectations.