The plan is clear as mud. Robbie Williams is making his biopic Better Man in Melbourne and he’s putting on two concerts to film a recreation of the 1998 Brit awards. So please wear 90s clothes – or don’t, no one will mind. You might be in the film, but the first rows will be filled with extras. And the concert is not just a concert; it is An Evening with Robbie Williams, which means we’ll also get a Richard Wilkins interview with him, plus the promise of “a guest appearance from a spokesperson from the set”. The Guardian is offered free tickets, on the condition we promise not to write anything. I buy one instead, because we have so many questions: why is one of the UK’s most successful musicians making his movie in Melbourne? Is it true that Williams will be played by a CGI monkey? Bohemian Rhapsody, this is not; I suspect Better Man will be closer to the out-and-out weirdness of Aline, which saw an adult actor play Celine Dion as a baby. At least the fashion rules are clear. On Sunday night, the second of the two shows, a sea of flannel flows towards Rod Laver Arena; there are more mullets here than the Saints’ changing room. It is easy to spot who won’t make the final edit: the fan in her “Williams ’03” jersey for instance; same for the guys puffing away on vapes, or those who won’t put down their iPhones. But even Williams is an incongruity here: a craggy 48-year-old recreating a performance from when he was 22. He doesn’t seem to have a better grip on what is happening: he tells a story about the previous night, when he came out and noticed how young the crowd was. “I was like, ‘Look at me in Melbourne, being a young person’s thing!’ It’s like I’m fucking TikTok. Then I realised, they’re all actors.” Then later, to someone at the front in the middle of a song: “Are you an actor? No? Well can you act like you’re having a good time, for fuck’s sake?” An evening with Robbie Williams turns out to be chaotic in the best possible way. Williams is 40 minutes late; two friends next to me have a fight, cry and make up all in the time it takes for him to come out. More than one person is double fisting Canadian Club. But as soon as he arrives, the bored, drunk energy in the room immediately dissipates: how can you not be swept away by a man who comes out to his own name being sung to O Fortuna? “I’m Robbie fucking Williams!” he bellows, as way of introduction. “This is my band, this is my arse, and tonight, Melbourne is ours!” We’re there to film a recreation of Williams’ performance with Tom Jones at the 1998 Brits – his first appearance at the awards after Take That split. Williams doesn’t remember it: “I don’t know what you can remember after doing three grams of coke and drunk a bottle of sambuca. I’ve seen it on telly.” Jones isn’t there because “he is too fucking expensive” – so instead we get “Australia’s premier Tom Jones impersonator”, who comes out to sing Land of a 1,000 Dances with Williams. We do the scene twice, everyone hooting and cheering with gusto. It is bewildering. It is great fun. And holding the night together is our mad ringmaster, who flashes his nipples and gallops around the stage and, occasionally, forgets why we’re all there: he sings the opening lyrics of Angel, then remembers he was supposed to tell everyone to sing along so they can film it and has to do it again. Perhaps unsurprisingly, Better Man will be for “the over 18s”, Williams tells Wilkins – “because it is my life, it is what I got up to. It’s not anodyne, it’s not vanilla, it is not PH7. It is warts and all. It is the drugs, the ups, the downs, the women, the sex.” While the British press became preoccupied with his interest in UFOs and sniffy about his move to LA, Australia has always loved Robbie unconditionally, I suspect because of a nationwide belief that he’d be good fun at a barbecue. So no one at Rod Laver minds the stop-start nature of the evening, or leaves when our “spokesperson from the set” comes out: the film’s director Michael Gracey, who made The Greatest Showman. We all want Robbie’s mad monkey film to be good. “You have been trojans,” Williams says. “I am so grateful, Melbourne.” On the walk home, I watch the 1998 Brits performance. The crowd was good, I think, but maybe we were better tonight. And Robbie, so beautiful and manic then, is probably better now too: less wild-eyed and more settled, and just so happy to be there on stage, beaming down at the wall of faces smiling back at him.