For all my fears of security overkill, everything went off smoothly. There were black screens around the theatre entrance, as if some terrible accident was about to happen. Which, in a way, it did. The show's really not very good, not what anyone except the die-hardest of fans would really really want.
The story's a mess but the sound is terrific. And the buzz, well, phenomenal. Joan Collins and Michael Caine stepped up to the plate. Barbara Windsor sat along the row from me, looking good; "It's not having to be on the EastEnders set first thing after a dawn wake-up," her husband Scott Mitchell told me as they squeezed by to their seats.
Of course the Spice Girls were all there, sitting together, though Victoria stayed a few seats apart with David, but I was surrounded by the Jesus Christ Superstar mob: a very slimmed-down Chris Moyles, Alex Hanson (with wife Samantha Bond) and Ben Forster. Simon Fuller beamed across the front stalls and Ruby Wax went charging madly about looking for something. I think she said she had her dogs with her, and she had a rucksack on her back, but no woofs emanating. Then she found Barbara Windsor and calmed down.
The pub next to the theatre served as a Press room, and journalists were delighted to discover that the place was operating as a free bar, both before the show and during the protracted interval. Even so, the show was down well before 10pm, which makes it all the more surprising that several overnight reviewers - Guardian, Telegraph, Independent - had chickened out of the first night challenge and attended the last preview (these first night waverers had similarly ducked out of Privates on Parade and sneaked in on Saturday's preview).
This reminded me that the Royal Shakespeare Company used to start in Stratford-upon-Avon at 6.30pm, an excellent practice for those filing overnight and also for those driving home... few plays of the Bard run for under three hours, so there was always a good chance of breaking that psychological pre-10pm barrier. Then some jobsworth pushed the opening time back half an hour and it's stayed there ever since. I shall urge Greg Doran to return to what they call "original theatre practices" at the Globe.
The last time I spent an interval in the pub next door at the Piccadilly was at the opening of Which Witch, a Norwegian musical which scored a critical "nul point" and which allowed every reviewer to open with a howl of, "Why, why?"
The rumpus over the bad reviews escalated into a diplomatic incident and there was even talk of Norway withholding its annual gift of the giant Christmas tree in Trafalgar Square. And then there was Metropolis, and David Essex in Mutiny on the Bounty, and Moby Dick. Oh my god. And I even recall a grim musical about a seasonal strike in a Christmas cracker factory called, I'm afraid, Pull Both Ends.
No, the Piccadilly is not a happy hunting ground for the musical theatre and I can't say I'm full of optimism for the chances of Viva Forever! there. More like Viva A Couple of Months!, I reckon, though that's possibly discounting the fervour of the Spice Girls fans, who kicked up an enormous racket outside before the opening.
The Girls themselves were pretty pleased, too. They filed on to the stage at the end while writer Jennifer Saunders and producer Judy Craymer stood in the aisle with their arms round each other like a couple of naughty schoolchildren.
Mel C thanked a great cast. Mel B said simply, "That was effing great." Emma Bunton was excited. Victoria thanked Judy, Jennifer and her family. And Geri Halliwell announced that Judy Craymer was a true woman of girl power and thanked her for making the Spice Girls dream come true.
Which is interesting: they always wanted a West End musical, and now they've got one. As with The Bodyguard, all the real energy and work went into the finale, and there was the most tremendous company dance-off. The guests filed out to the waiting red party buses, and you felt the night, for some people at least, was only just beginning...