The 36-year-old actress likes to feel "calm and neutral" in simple clothes when she isn't filming because she spends so much time on TV and film sets having to "dress up".
She admitted: "This is as jazzy as I normally get. My wardrobe is mostly black because I dress up for a living, and it makes me feel calm and neutral."
The 'Black Mirror' actress can next be seen in 'Misbehaviour', in which she plays Jennifer Hosten, the Miss Grenada who became the first black woman to be crowned Miss World and she admitted researching the role gave her less "judgement" about beauty contests.
She said in a recent interveiw: "I came to [the part] with an air of judgement, of, oh, you know, beauty queens, but I've become more open-minded as to what that represents. I think it's very easy now to look back and say, 'Why would you do that? It's so superficial.' What's interesting is that rebellion can often be a luxury."
As part of her research, Gugu visited Grenada to meet with Jennifer.
She said: "She's in her seventies now, and she's got such a regal presence, such posture, these bright, bright eyes - she's very demure, quite proper but very centred."
When Jennifer won the contest in 1970, the competition was famously targetted by female protestors and Gugu admitted watching footage of the ceremony was "shocking" because of how sexist it was.
She said: "I watched the whole ceremony and it's shocking, particularly the bit where the women all have to turn round to show their bottoms.
"It definitely makes you realise quite how far we've come."
This article was origibnally on Bang Showbiz