The creations of The Crown’s costume designer, Amy Roberts, also informed Anderson’s transformation. Known for her Aquascutum suits, sensible Asprey handbags, and an immovable bouffant hairstyle, Thatcher’s version of power dressing was a crucial part of her image. Getting the look right involved trial and error on everything from the tailoring to finding accurate makeup for the era. “I was sitting in the hair and makeup chair while they were trying to work out their contributions, and when I would get closer to looking like her, I would take pictures of the mirror because it was like, ‘Oh my God, oh my God. Look, there she is.’” says Anderson. “That was quite a long process. [Finding] the particular blue eyeshadow that felt like it was from the ’70s and ’80s, but it wasn’t quite so opaque, and the particular base that wasn’t too heavy for 4K HD. All of those choices very carefully thought out. So when they would try different versions of things, some looked more like her than others and it was always exciting when we got closer.”

In recent years, actors have disappeared into their roles as famous figures through the use of undetectable prosthetics or CGI magic—think Charlize Theron’s uncanny Meghan Kelly in Bombshell or computerized anti-aging allowed Robert DeNiro to play three decades in the life of gangster, Frank Sheeran in The Irishman. Technology’s helping hand can enhance performance, but Anderson opted to go the old fashioned route. She embodies Thatcher through subtle changes in posture, voice, and movement, a decision she felt appropriate. “We were a similar age, so it didn’t feel like I would need to make myself look older,” says Anderson. “We have a similar nose; we have somewhat similar eyes as we’ve both got hooded eyelids.” Initially, the idea of wearing a dental prosthesis was floated, but it proved distracting. “She had very distinctive teeth. They weren’t great, and she had them capped a couple of times while she was in office,” says Anderson. “Someone built a prosthesis that matched, but it was too much and didn’t look natural at all. We tried different ways of coloring and staining, making a gap, but in the end, we decided against it. [Instead] I figured out a way to hold my mouth so that I had more of an overbite. The mixture of that, the tilted head, and her movements wound up being enough.”