Warning: This article contains minor spoilers for the Downton Abbey film.
Rob has played Downton staff member Thomas Barrow in the ITV period drama since its debut in 2010, with the character eventually promoted to head butler in its final series.
Barrow was revealed to be gay early on in the show’s run, which is explored further in the new film.
Speaking to PA news agency, Rob said Barrow’s storyline almost feels like a “separate film”, revealing: “You see Thomas discover a whole new world, and that is closer to who he is and there is a joy there, but then that joy may get taken away but it’s a very emotional, Thomas’s journey.”
He continued: “It also hammers home what it was like to be a gay man in those times, it was horrific and it’s brought back and it just shows how different it was.
“It must have been so hard for him and that is why the people warm to him and root for Thomas now, and they certainly will in the film if you watch it.”
The Downton Abbey film centres around a royal visit to the Crawley family’s estate, and the effect this furore has on both its residents and staff.
All of the show’s original cast members have returned for the new film, including Hugh Bonneville as Lord Grantham and Dame Maggie Smith as the always-iconic Dowager Countess.
Downton Abbey which hits cinemas on Friday 13 September.