The 26-year-old actress looks younger and prettier than her Lady Edith Crawley character, with beautiful porcelain skin and sparkly eyes.
"There's something about wearing clothes that your great-grandmother might have thought were nice that makes you look older," she says.
"Me and Lily (Lady Rose MacClare) were in hysterics one day because we were both wearing dresses and pouring tea and it was like we were doing old women acting." Laura adds that Edith’s 1920s hairstyle is also a "good disguise".
"It puts me in that era and in my Edith zone," she says. "I'm a lot scruffier."
Edith gets to wear more gorgeous glamorous dresses in season four, and she experiences a blossoming romance.
"There's a real ’lets go for it' attitude with Edith, which I think adds to the story of her brother-in-law being killed in a car crash and having just survived World War I," says Laura, who trained the Bristol Old Vic Theatre School. "Life is scary and short."
Her character, who writes a newspaper column, has been described as a period drama version of Sex and the City character Carrie Bradshaw.
"I would joke on set that I was going to sit there going 'I couldn’t help but wonder…'" she says, adopting the accent and well-known phrase of Carrie. "I'm a bit Sex and the City fan."
"We have all these amazing props on set, original copies of newspapers, and and I get a big kick out of it because it doesn’t seem that far away from what we see in modern day magazines. They claim more things in face cream adverts than we do now!"
After being initially trying to woo Matthew Crawley, who later became her sister's husband, then being jilted at the alter by Sir Anthony Strallen, Edith seems to have found love with newspaper editor Michael Gregson.
"It’' lovely for me that the romance is so different to anything we've seen on Downton before," says Laura. "He's not arriving at the house with a horse or anything, it's a very much a modern take – somebody she's met at work really and a self-made man."
The hitch, however, is that her suitor is already married. "Even dining out with a married man was quite shocking," says Laura. "It's really fun to play."
The developing storylines have kept viewers gripped and have helped Downton to become Britian's most successful TV export with a global audience of 120 million.
"We are all kind of fascinated by how it happened," says Laura. The series has been a particular hit in the USA. "People will just very confidently talk about you in the same breath as Mad Men," she says. "I'm a big fan of all these American shows, and it’s really wonderful and gratifying."