The 46-year-old pop star turned heads with some of her eye-popping outfits in the 90s - including her famous Union Jack dress - but she is now keen to adopt a more conservative look for the group's much-hyped reunion.
A source explained: ''All the girls have fully embraced this zeitgeist reunion, even if it means wearing clothes they wouldn't necessarily pluck from their own wardrobes.
''But Geri is a married woman, with kids of her own, and isn't so keen to revert back to the Ginger Spice of old.
''Understandably she wants to look more age-appropriate.
''She doesn't want to be prancing around the stage in a sequinned Union Flag mini-dress with her boobs out and wearing leather knee-high boots.
''Fans have been taking the mick out of her sedate, lady-of-the-manor look while even the girls have made a couple of jokey remarks about her posh new Boden housewife aesthetic.''
Acclaimed theatrical designer Gabriella Slade has been chosen to select the outfits for the band's comeback tour.
But Geri - who has kids Bluebell, 12, and Montague, two - is keen to present a more refined image of herself.
Speaking to The Sun on Sunday newspaper, the insider shared: ''Gabriella has done a brilliant job on the costume front, and she and Geri have provisionally agreed on a more refined yet theatrical version of that [Union Jack] dress.''
Meanwhile, it was recently reported that Mel C is taking the lead when it comes to the Spice Girls' musical direction for their tour.
The singer - who is known as Sporty Spice in the group - has made it her ''priority'' to ensure that she and her bandmates Geri, Mel B and Emma Bunton's vocals are in tip-top shape by using the same musical director she worked alongside on her solo music.
A source said: ''The girls each have a House of Spice theme complete with groups of dancers branded as Baby, Scary, Ginger and Sporty, which will certainly entertain.
''But Mel insisted she brought in a musical director she has worked closely with on her solo material to boost the vocal performances and make sure the music hits the right note.''
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