Holly Willoughby and Emma Bunton ‘snogged on night out’ claims Mel B

Mel B, 43, sensationally revealed last week that she'd had a boozy night of passion with Geri, 46 – who is said to be furious with her, as her daughter Bluebell, 13, could read the story. A worried Mel C, 45, hinted the fallout could ruin the reunion, responding to Mel B's exposé by saying, "That's it then, the tour is off."

Geri married F1 boss Christian Horner in 2015 and replaced the tongue-poking andpeace-signs with spiritualism sessionsand cookery classes. She has a society neighbour, Lady Joanna Wellesley, and a menagerie of goats and donkeys at her country manor. She also reportedly stopped a photo shoot with the Spices so she could meditate – and her new lifestyle is said to have irked Northern lass Mel B.

The Spices sacked old boss Simon Fuller in 1997, amid reports he'd had a relationship with Emma Bunton, 43 – which they both denied – but he's involved with the tour in partnership with Mel C's Modest Management agency. He's also responsible for Brand Beckham – which won't sit well with the girls if they reportedly continue to clash with Posh, 44.

Fans want a guest appearance fromPosh, but she doesn't get on with Mel B. Mel reportedly described Posh as "a bit of a bitch" in an interview last month, and allegedly told her to "f*** off" during a phone call last year. She then dressed up as her for Halloween. Posh also said the girls used to switch off her mic on-stage!

Their 2007 comeback single Headlines was a flop, limping into the charts at number 20, and they fear the same will happen with the tour. Emma suffered anxiety before tickets went on sale, while Geri is reportedly taking singing lessons to avoid embarrassment.

Allegedly without the girls' say so, tour managers booked Jess Glynne as their support act, agreeing to a hefty £1.3million fee. The Spice Girls, who are rumoured to be pocketing £2.2m each, are said to be furious, suggesting tensions will rise in the dressing rooms. Jess, however, said she only agreed to the tour as she was such a massive Spice Girls fan and wanted to "hang out" with them.

Stage costumes are causing problems as the foursome struggle to agree whether their fans want to see them wearing their '90s outfits – think Union Jack dresses – or more grown-up attire. While Mel B is apparently "desperate to relaunch herself as an edgy, sexy star to compete with the likes of Rita Ora", Geri wants a more wholesome image to appeal to the older, original fans.

It's no secret that money is a big motivation for the tour. But Victoria will still make millions without stepping foot on stage, as she owns an equal stake in the band's brand. This has reportedly caused fury among the band members.

The Girls are reportedly discussing having a "fifth Spice". Comedian Jack Whitehall and superfan Adele have offered their services, while The X Factor's Saara Aalto revealed Mel C told her she could join. But would that mean splitting their earnings even further?

Although Emma is seen as the sweet one, she's no pushover. She may have forgiven Geri for quitting the band in 2003, but reveals that she won't stay quiet if the Girls squabble. "I was never afraid to say exactly what I thought. It's still the same now," she said recently.