They will be back on stage together in only two months' time, and rehearsals are due to start in London in a fortnight.
The remaining Spice Girls — Geri Horner, 46, Emma Bunton, 43, Melanie Brown, 43, and Melanie Chisholm, 45 — have begun workouts with personal trainers to get them into shape for the 13-date reunion, which will culminate with three sold-out nights at Wembley Stadium in June.
But as the juggernaut prepares for a "final" tour, 12 years after the last one, all is far from rosy in the world of Girl Power.
Behind the scenes, there has already been one "almighty humdinger" of a row over money, plus simmering disagreements over everything from costumes to lyrics.
Add in the fact that Victoria Beckham, 44, who refused to be part of the reunion, is set to make millions from the tour without even having to go on stage, and that Geri, who now fancies herself as "the real Posh Spice" since marrying a millionaire motorsport executive, has been driving the others 'up the wall', and you've got the makings of a very fractious foursome.
THE "HUMDINGER" ROW
Singer Jess Glynne, 29, who has had seven solo number one singles (the Spice Girls have had a total of nine), will be the support act on the tour.
Sources indicate that she is to be paid £100,000 ($NZ192,000) a show — a total of £1.3 million ($NZ2.49m) for the dates. This has caused enormous friction between the Spice Girls and their artist management company, Modest Management — they have been arguing about it all year, and were still at daggers drawn this week.
A source said: "There has been a huge breakdown between Modest and the Spice Girls. Their feeling is that Modest took on Jess Glynne on a huge fee without consulting them.
"There has been a dispute, with the girls saying they aren't going to pay it, but it turns out that they have to pay it. Now Modest are saying that they have to pay all of it.
"Their feeling is that they didn't actually need support on the tour, and that Jess Glynne is not remotely in tune with them or their fan base, which is much older. They are raging about it."
Negotiations have been handled largely by the mild-mannered Harry Magee at Modest, who is known for his patience.
However, a source said: "Modest are finding them very difficult. They are used to looking after One Direction and Little Mix, who do as they are told.
"They've never dealt with anyone who behaves in the way that the Spice Girls do, but the girls are all used to managing themselves. They really don't want to be pushed around."
For her part, Jess Glynne has said: "I think it's an amazing thing and an honour to be on the road with them because we all stand for something. I think that's a beautiful thing."
I TELL YOU WHAT I WANT!
Mel B, 46, really needs the money. Her lucrative job as a judge on America's Got Talent was axed in February, meaning that the mother of three will have to manage without the £2.5 million ($NZ4.8m) a year salary she earned from the show.
Simon Cowell has apparently been promising to put her on the panel at Britain's Got Talent or on Australian X factor, as he rates her as a television performer and is very loyal to her.
Mel left her second marriage, to film producer Stephen Belafonte, claiming emotional abuse, and is virtually penniless, having apparently blown her £38 million ($NZ72.89m) fortune during the union. Last year, she claimed she had only £800 ($NZ1,536) in the bank after their split. She has to pay Belafonte — the father of her youngest daughter, Madison — ongoing spousal support and there were large legal fees after their bitter divorce.
Last week, she also went to a mediation session with her daughters' former nanny, Lorraine Gilles, to try to settle a lawsuit with her — again, Mel is bound to be incurring hefty legal fees. A source said: "Mel B needs the money the most — that's still very much the case. It depends on how much she gets, but at least half of it may go in legal fees alone."
It's said that Sporty Spice Mel C — who has a ten-year-old daughter, Scarlet, by her former boyfriend, property developer Thomas Starr — will also be glad of the money, although she had arguably the most successful solo career of the five Spice Girls, and is said to be worth £27 million ($NZ51.8m).
Emma Bunton has quit her job as breakfast show co-presenter with Heart FM and is about to release a solo album. She's said to be worth £21 million ($NZ40.33m).
The tour is expected to net them between £6 million ($NZ11.5m) and £10 million ($NZ19.2m) each, depending on sales of merchandise and albums.
THE WHATSAPP DELAYS . . .
All decisions are debated by the girls over group WhatsApp messages, and it can take many weeks to get anything signed off.
Emma Bunton said in an interview this month: "We do make decisions together, which does take a little bit longer, but that's how we do it."
So far, they have agreed on the choreographer, the choreography and the hiring of dancers. They have also agreed on the catering, which seems to be mainly sushi. And, after a bump or two in the road, they have chosen their "very spangly" stage costumes.
"There is no expense spared on any aspect of the tour. They are throwing money at it, and they all agree that they want it to be a truly spectacular show," says a source.
All four women started work with personal trainers in February in order to make sure they have the fitness levels required to pull off the dance routines, and they have all started independent dance rehearsals, plus work with a vocal coach, to "remind them" of their Spice Girls repertoire.
Geri says that her 12-year-old daughter, Bluebell Madonna, finds the routines horribly embarrassing and begs her to stop.
. . . AND SPATS OVER 'TARTY' COSTUMES
All the old problems are there still, simmering away. "So far, it is mostly niggling, but bear in mind that they've barely been in the same room yet," says a source.
There was a row between the two Mels over changing the lyrics to 1997 hit Spice Up Your Life. The song refers to the "yellow man in Timbuktu" which Mel C thinks needs to go, but Mel B disagreed about what should replace it.
There was another row about costumes, with Geri and Mel B taking opposing views. Mel B thought that the proposed outfits were too tame — she is known for her body confidence and bold, bordering on vulgar, taste.
"Geri kept saying everything needed to be 'fun' and 'iconic' but 'suitable for mature women', says a source.
"What she meant was that she didn't like the stuff Mel B liked. She thought it was too tarty."
There were also "words" after their joint appearance on the Jonathan Ross TV show last November. "Geri wouldn't let anyone else get a word in, which is typical her," said a source.
"There was exasperation afterwards. They aren't doing any more joint interviews because no one else gets to speak. In any case, they've sold out the tour so they don't have to."
The source added: "They question absolutely everything and it is all being done by each woman personally, not their managers.
"The talons are out. There is some dread about what is going to happen when they have to be in the same room as each other for a long period of time.
"It is a re-run of old arguments —who is good at picking things up quickly, who is responsive, on time, all of that. Mel B can be quite impatient."
BRING ON THE ENTOURAGES
The four women will have their own hairdressers and make-up artists, and each is making separate travel arrangements for herself, her family and entourage.
All the girls' families are coming on all the dates — it will be "a real travelling circus," says a source.
Broadly speaking, the two Mels are buddying up, with Geri and Emma on the other side.
This division is nothing new — in the early days it is a matter of record there were physical catfights between the five Spice Girls.
Mel B and Geri were the most explosive combination, with Geri quitting the group in 1998 after a series of confrontations with her.
WATCH OUT FOR 'LADY GERI'
Geri is proving to be a bit of an issue. The daughter of a cleaner from Watford, with a background in podium dancing, post-Spice she has reinvented herself.
She now lives with husband Christian Horner — boss of the F1 Red Bull racing team — on a 15th-century country estate in Oxfordshire, with horses, goats, donkeys, chickens, dogs and cats.
Apparently, her lady-of-the-manor airs are getting right on everyone's nerves.
Of her former bandmates, only Emma Bunton attended Geri's wedding in 2015, which says something about their friendship.
"She talks complete nonsense all the time which is very irritating," says a source.
Her assertion in a recent broadsheet newspaper interview that war-time Prime Minister Winston Churchill was the first Spice Girl is, perhaps, a case in point.
"More than that, Geri also thinks that she is the leader of the group, but the others don't want that," added the source.
WILL THEY BE THE WIZARDS OF OZ?
Promoters have promised the girls up to £80 million ($NZ153.6m) between them if they extend their UK tour to America and Australasia, but they have not been in agreement and so have missed their chance to do that this year. Mel B was keen, whereas Geri — who also has a toddler son — didn't want to make the commitment.
A source said: "They will do it next year if they want to, they don't care if they have missed the chance. They are doing everything very deliberately and very much on their own terms."
MRS BECKHAM CASHES IN BY STAYING AT HOME
Worth £240 million ($NZ460.97m) and with a fashion empire to run, Victoria Beckham has shown little interest in the reunion and is not taking part in the stage shows. Asked if it was a hard decision not to join the group on the tour, she said: "It wasn't."
This will surely have come as a relief, because she and Mel B have long had a tricky relationship and they fell out during the 2007 comeback tour.
Mel B has said she was under the impression that Victoria was on board for the reunion tour during a meeting held last February at Geri's house.
In fact, Victoria attended merely to show support for former Spice Girls manager Simon Fuller, who is a co-owner of her fashion business.
All present at that meeting signed legal documents to "sort out" the question of rights to the Spice Girls names, which were "in a bit of a mess."
As a result, both Victoria Beckham and Simon Fuller will profit hugely from the forthcoming tour, even though she won't even appear during it, and he has 'co-manager' status with Modest Management.
So how much will Victoria get? A source suggests £2.5 million ($NZ4.8m) "plus" — with Fuller a little less, adding: "That meeting was all about getting Simon Fuller to have a percentage of all Spice Girls money, and Victoria was very much in favour of that. A percentage goes to Victoria and a percentage to Simon Fuller.
"What it means is that every time anyone buys anything to do with the Spice Girls, she gets her slice. The others are just having to suck it up."