John Heffernan is a British actor. He had his career beginnings in the late 2000s, debuting in the TV movie King Lear. He later appeared in 2 episodes of The Hollow Crown. After this, he played Ashley Roehampton in the ITV series Love and Marriage. At the same time, he made his film debut in Having You. He went on to have guest roles in Outlander, Ripper Street, and Sons of Liberty. He also became known for his roles as Henry Lascelles in Jonathan Strange & Mr. Norrell and Jaggers in Dickensian. He simultaneously starred in the 2015 film Eye in the Sky. Heffernan next starred in the films Crooked House and Official Secrets. Also, he played Dr. Simon Marr in The Loch and Sam Spence in the miniseries Collateral. He recently portrayed Matthew Elliott in the TV film Brexit: The Uncivil War and Jonathan Harker in Dracula.