The girl group were formed on Popstars The Rivals back in 2002 and were one of the first - and even to this date, very few - success stories from such shows.
Reflecting on the past 15 years, Sarah said this month: "I don't know where the time has gone. I get really nostalgic when I think about being in Girls Aloud.
"I found a CD of our Radio One Live Lounge performances the other day and it was so nice to listen back and hear us all bantering with each other. I really miss performing with the girls on stage."
Speaking of a potential reunion for the group's 15th anniversary later this year, Sarah told OK! Magazine: "I don't think it'll happen any time soon, but I'd love the chance to do something again. A lot of our fans would love us to comeback so we'll have to wait and see what happens."
She continued: "We've not seen each other properly for years but Nadine and I still message each other. I don't live near any of them so its hard to make time to see each other.
"Cheryl, Kimberley and Nicola are really close but Nadine and I are much more independent.
"We might have gone our separate ways but we were like sisters for years, so I'll always care about them."