The Big Moment comes well over an hour into the second of Pete Doherty’s An Evening With. Pete Doherty gigs at the Hackney Empire, and what’s in truth become by now a somewhat rudderless sort of show is brilliantly redeemed when Pete announces his former Libertines accomplice, Carl Barat.

I’m actually at the bar when it happens, the Empire suddenly a cauldron of unbridled hysteria, the noise of the crowd an incredible thing to hear, a demented din, people screaming, weeping, hollering.

The audience tonight has so far been unusually restless, almost pathologically disinclined to sit in their seats and pay anything more than passing attention to what’s been happening on stage. They are in and out of the bar, in and out of their seats, fussing with mobiles and spilling drinks, talk loudly over the opening solo set by Pete’s friend, handsomely be-hatted Alan Wass, barely noticing that three numbers in he’s been joined by Pete and then virtually drowning out Pete’s next guest, Bert Jansch.

I don’t want to sound precious and I know we’re not in a fucking church, but the irksome yakking yahoos around me quickly put me in a fiercely oppositional mood. The whey-faced weasel sitting in front of me is lucky to escape a thump on the head when during Pete’s duet with Bert on the latter’s classic heroin song, “Needle Of Death” – which Pete had essayed nervously the previous night, but sung year with fragile perfection, investing the original’s cautionary grimness with a beatific fatalism – he insists on chatting VERY LOUDLY to his slack-jawed girlfriend about, of all things, kitchen fittings.

The night before, Pete, looking well and sounding better, had been in full control of the crowd, playing brilliantly with their expectations and affection, offering up great versions of old favourites like “Killamangiro”, “Music When The Lights Go Out”, “What Katie Did”, “In Love With A Feeling”, “Albion” and “What A Waster” – which ends with the spoken plea, “Save me from the Taliban” – and the more recent “The Blinding” and “Love You But You’re Green” (“It’s blood from broken hearts that writes the words to every song”). There are gust appearances from Kate Moss on “La Belle Et La Bete”, on which guest rapper Lethal Bizzle also a verse, and a clutch of new songs – including “John The Baptist” and “Do You Know Me”.

About two hours into what would eventually be a three-hour show, Pete takes a fag break and returns for a rousing singalong on “Fuck Forever” and “East Of Eden”, before he’s joined by The General who takes the lead on “Pentonville”, the set ending with a rousing “Time For Heroes”.

“Thanks four your support in troubled times,” he says, and splits, triumphant.

Tonight, prior to Barat’s appearance, Pete seems distracted by the crowd’s restive mood and in trying to hold their interest appears to lose interest himself, even on welcome oddities like “Pipey McGraw” and “Cyclops”.

Now, though, as Pete and Carl roar through virtually a full set of Libertines songs, the roof is coming off the venerable old Empire, which in its long history has probably known few scenes like this, the cheers that greet Barat’s tap-dancing routine on their cover of Mama Cass’ “Dream A Little Dream” quite deafening.

There’s some confusion towards the end of all this when after “Time For Heroes” it’s announced there’ll be an interval, which causes a stampede for the bars. A couple of minutes later, Doherty and Barat are back with Babyshambles guitarist Mick Whitnall on harmonica for a shaky version of “Albion”. Carl takes lead vocals for part of this, which probably would have been a better idea if he’d known the words. They then play “The Delaney” and at that point they look like they might play for another hour. Then some twat in the balcony throws a full pint at the stage, which lands between Pete and Carl. God knows, they’ve had worse things chucked at them, but after a withering glance at the balcony, Pete’s off and even as the crowds are flocking back out of the bars the fire curtain comes down, and that appears to be that.

A couple of hours later, getting home, however, the texts and call start coming through with wild descriptions of Pete and Carl “busking” outside the Empire, which makes me seriously worried for them at the hands of the rabid fans who’d been milling around the venue as we left. Turns out, though, the pair had played an impromptu version of “Can’t Stand Me Now” from a backstage window.

Where will it all end?