That strength helped them hold firm when, in the early days, managers tried to change the band's line-up; and it made them fight for Cardboard Box to be their debut single, against record label advice.
Studying R&B taught them more than how to harmonise – it showed them how the music industry, particularly in the UK, can be stacked against black women.
Time after time, promising artists like Jamelia, Sadie Ama and even Raye have been let down by labels that don't know how to promote R&B to a UK audience. Others, like Mahalia and Ella Mai, have focused on breaking the US, where the genre has deeper roots.
"That's the music I love the most, and it's probably the hardest music to sell in this country," Radio 2's Trevor Nelson told The Guardian last year. "It just is. It's always been."
On the album track, I'm Just A Girl, Flo address that situation over a dark, electronic beat.
"How many black girls do you see on centre stage now? / Yet you wonder why they going to the States now."
"I actually think we've been pretty lucky, but we've definitely seen little comments here and there, or people not being accustomed to the music that we make," says Douglas.
"When we go out in the UK, people love R&B, but I think people who make the decisions in the industry in the UK aren't so familiar with it. So I think it can make people feel a little bit unappreciated.
"I think what sets us apart is that we speak about it," says Downer. "We're all thinking it, all the R&B artists in the UK. We're not content with making music and it reaching fewer people.
"We're very happy that we're starting to be seen as the catalyst for change," adds Quaresma, "but it's obviously a problem".
For now, the trio are playing the game. The first single from Access All Areas was the irresistibly catchy Walk Like This, a pop hit in R&B clothing. Then they targeted urban radio with the slinky, serpentine grooves of Caught Up.
"We're constantly doing a push and pull between 'this is a bit more pop-leaning, and this is more R&B'," says Downer.
"We have to be open to putting our pop foot first sometimes, because of the world that we live in. But a few years down the line, it's gonna be different."