Nigel appeared in the ITV1 period drama for the first time last night (6 October) as guest valet Mr Green who, after appearing charming, went on to beat and rape married maid Anna Bates.
Viewers were given a warning of 'violent scenes' before the programme aired, however they were unaware of exactly what was to come. Some fans have since spoken out, saying the scenes were too "upsetting".
Speaking about the storyline on This Morning today (7 October), Nigel said: "It was a shocking and bold storyline and something that when I was sent the script and read it, was kind of amazed and excited, if that's the word to use.
"For a show like Downton it really leaped out as a bold and risky idea.
"We had this man turning up who was a bit cheeky and over confident, but we didn't want to signal what could possibly be the shadow lurking in him.
"We wanted to go for something that, as it would in real life, be very shocking."
Downton Abbey is set in 1922, when rape was never mentioned or reported to the police. In the show, Anna confided in Mrs Hughes but swore her to secrecy.
"To have female voice was still a very difficult and new idea," Nigel added. "We're still dealing with that situation, which some would argue hasn't changed that much now."
Meanwhile, on getting his role in Downton, Nigel admitted that he had originally auditioned for a part upstairs, rather than downstairs.
"When I went for my audition it was for Tom Cullen's role as Lord Gillingham and I went in and did my best Lord audition," Nigel explained.
"I even ironed my shirt, I had perfect hair and I charmed the socks off the bosses, or so I thought, and I was thinking, 'That went well'.
"My phone went the next day and it was my agent to say, 'They loved you at Downton, but they think you're much more suited to being downstairs...' So that's how it came about!"
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