If you want to understand how the characters of The Crown are feeling in Season 4, look no further than the clothes on their backs. In a behind-the-scenes video, costume designer Amy Roberts –– who took over from Michele Clapton and Jane Petrie in Season 3 –– reveals how she used color palettes and fabrics to bring additional layers to the story.

“In our studio, we have a visual journey of each of our main characters, with textiles of that period,” she says. “You’re just in that world straight away.”

Roberts says she “had to really pull everybody into the ’60s” in Season 3, which meant using “big sherbert-y colors.” Season 4, which begins in the late 1970s and stretches into the 1980s, relies on a more muted palette. “Moving into the ’80s now, we’re holding on to that color, but you imagine it mixed a little bit muddier,” she adds.

Season 4 also sees the introduction of two major new characters: Diana Spencer, the future Princess of Wales played by Emma Corrin, and Prime Minister Margaret Thatcher, played by Gillian Anderson.

“She was obsessed with clothes,” Anderson says of the Iron Lady. One of the first scenes she filmed depicted Thatcher’s first visit to Balmoral, where she makes a series of disastrous sartorial faux pas. First, she shows up far too early for dinner, dressed to the nines in a bright purple gown that Anderson says she adored. Then, when the queen invites her stalking, she arrives in a sharp electric blue suit, standing out like a sore thumb against the muddy backdrop of the Scottish Highlands. Those moments reflect the stark contrast between the working-class born Thatcher and the royal family, heralding one of the central conflicts of the season.

Later, when Thatcher is about to declare war over the Falkland Islands, her clothes also reflect that militaristic bent.

Diana undergoes a similar style evolution. “Fashion is such an integral part of Diana’s journey,” Corrin says. “She goes from being a very normal girl with very average taste in clothes. By the end, you leave her and she’s really found her voice in her clothing.”

To understand this, Roberts suggests looking at the first image we get of a teenage Diana dressed up in a whimsical costume for A Midsummer Night’s Dream, and the final shot of her in Season 4, which takes place more than a decade later. Dressed in a sharp black suit, Diana has traded in what Roberts calls her “bright woolen, almost home-knitted jumpers” for a more polished look as she attends a dramatic Christmas at Sandringham and takes stock of her troubled marriage to Prince Charles (Josh O’Connor).

Still, when it came to Diana’s fashion, there was one costume Roberts simply had to nail: her 1981 wedding dress. Watch an outtake from Corrin’s fittings in the clip above, and get more insights on the fashion from Season 4 of The Crown ahead of the Season 5 premiere on Nov. 9.