The 45-year-old singer - who was known as Ginger Spice in the group's heyday - shocked fans around the world when she decided to leave the band midway through their 'Spiceworld' European tour 20 years ago today (31.05.18), and Mel says it came as a huge blow to the rest of the band.
Speaking to BANG Showbiz on the red carpet at the 63rd Ivor Novello Awards at London's Grosvenor House on Thursday (31.05.18), Mel admitted: ''It was devastating.
''We were on tour at the time, we had two shows left to do, and then we had a little break before a three-month tour of the US.
''To lose a member of the band was utterly devastating. We lost a member and a friend. She had her reasons.''
Mel - who was known as Sporty Spice - has compared their relationship at the time to a ''soap opera''.
However, they put ''water under the bridge'' as all five members reunited at Geri's house earlier this year to discuss how they are going to preserve the band's legacy.
Mel continued: ''We understood [Geri leaving] and now so much water has gone under the bridge. We've reformed.
''We're all great mates and looking at opportunities. It's part of life's rich tapestry. It's like a soap opera, the Spice Girls.''
As for their plans, Mel says whatever they end up doing, it has to be all of them wanting to do it and ''good enough'' for their fans.
She said: ''I will always be a Spice Girl, I'm incredibly proud to be part of the Spice Girls and I perform songs on stage at my solo gigs, I do Spice Girls songs but it's a tricky one because if there are certain members of the band who don't want to get on stage, I want to make sure whatever we do as the Spice Girls we all do.
''We want to make sure it's the right thing and it's totally befitting of the band and of the fans. We have incredible fans around the world who still support us so we just don't want to do anything that isn't good enough.''
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