“Good idea this, weren’t it?” shouts Alex Turner from the stage. It was billed as a momentous event and in the end, that’s exactly what it was. Arctic Monkeys have just played the biggest headlining gig of their career at LCC, in front of a deafening 50,000 people and a sea of inflatable hammers. More of which later, as it’s been a terrific day all round.

When we arrive at 3ish, I’m dismayed to discover that we’ve just missed the day’s opening gambit: a Beatles tribute band from Japan. Judging by the reaction of those around us, they were a hoot. Half an hour later, it’s clear that tales of Amy Winehouse’s recent demise are highly exaggerated. In mini-skirt, fitted lemon top and full Cleopatra war-paint, framed by backing singers and full brass regalia, she gave “Back To Black” the full works. “He Can Only Hold Her” and the title track were highlights, as was “Me And Mr Jones”, but a bold, sassy cover of The Specials’ “Hey Little Rich Girl” threatened to steal it. After nipping off for five minutes, she led a mass shout-along of “Rehab” before ending with The Zutons’ “Valerie”.

I have to confess that I missed the entire set from The Coral due to the abnormally long queue for the toilets, having waited nearly an hour for the first beer. But the mood of the crowd is good, no doubt helped by the appearance of a beating sun. On returning, I’m told the Scouse seven-piece did pretty rousing versions of “Goodbye”, “Dreaming Of You” and “Pass It On”.

By the time Supergrass take the stage just after 7pm, the vibe is so convivial that there are outbreaks of “dance-off” competitions amongst the crowd, rucks of punters gathering to watch various feats of nimble derring-do. Supergrass, as it happens, play a blinder. With a new album imminent, they kick off with what already feels like a classic, “Diamond Hoo Ha Man” (another live version of which is available as a free download from their website, incidentally). The rest of the set is tight, rambunctious and fizzing in all the right places: “Richard III”; “Grace”; “Caught By The Fuzz”, “Lenny”. There’s another new tune in there somewhere too, called “Rough Knuckles”.

And so to the main event. If there were any lingering doubts that Arctic Monkeys might be extending their reach with the biggest stadium gig of their short young lives, they were blown away in an instant. Just before 9pm, they trooped on to the pumping strain of the “Rocky” theme, before careening straight into current favourite, “Fluorescent Adolescent”.

By the second song, “I Bet You Look Good On The Dancefloor”, they’d instigated a frenzy. There’s not too much banter from the band themselves, but every utterance is greeted with booming cheers. After “Brianstorm”, Alex Turner asks if everyone’s having a nice day. After “Still Take You Home”, it appears someone’s thrown something on the stage. A miniature bottle of Bell’s whiskey, as it turns out. “How polite!” offers Turner.

For the most part, it’s the Monkeys on blanket-bombing form, a giant noise leavened by the observational pith of a surly Alan Bennett. By mid-set, a prolonged chant of “Yorkshire! Yorkshire!” has kicked in, but there’s a hiccup as the band’s sound cuts out during “Balaclava”. The Monkeys, oblivious, are still in full throttle. Ten minutes and an embarrassed apology later (“Let’s put it behind us,” says Turner), they relaunch with “Old Yellow Bricks”. “Mardy Bum” and a particularly potent “View From The Afternoon” stir everyone up again, before returning for an encore.

They do b-side “Plastic Tramp”, though I admit to not knowing it beforehand. In a quick vox pop of those around me, six other people have misheard Turner announce the song too. Answers vary from “Parrot Lips” to something equally odd. And with Turner moving on to keyboards, they close with “505” (The Rascals’ Miles Kane on guitar) and “A Certain Romance”.

The last time I saw Arctic Monkeys was two years ago, here in Manchester, rocking the sprung wooden floor of The Ritz. Back then, the thought of them filling out stadiums wasn’t inconceivable, just unlikely, given their stubborn sense of autonomy and their place in the music business. In the end, like everything else, they’ve now done it their way.

This review was written by ROB HUGHES