Oasis Finsbury Park, London

Some might say rock 'n' roll is dead. But not tonight

I saw Oasis in their finest hour, when 125,000 ardent fans sang their songs for them at Knebworth, five years ago. It wads the peak of Brit Pop's communal euphoria and Noel Gallagher has admitted several times they should have quit right then.

The time since, for the band and their fans, has been one long morning after. Noel Gallagher's song-writing inspiration seemed to have run dry. He and his brother Liam remain cocky pop figures, but the musical crown that gave that substance has been dashed from their heads.

Their new album, Heathen Chemistry, does signal some sort of tentative resurgence. But it's tonight, in another large field of hopeful fans, that is Oasis's best chance of getting the good times back.

It starts with a downpour, turning Finsbury Park to sludge. But this suits the embattled, unbowed mood of the fans, all a little older and wearily experienced than in the mad-for-it days of Knebworth, but, it seems clear, determined to pick up where that great day left off.

Oasis, certainly, are transformed from the uncertain, embarrassing figures of the past five years. An opening burst including "Hello'', "The Hindu Times'' and "Let it Out'', from all phases of their career, is uniformly urgent and energising.

As the rain magically clears, Liam, always the band's talent and talisman, stands at the centre of everything. Leaning into the microphone, snarling lyrics, and cajoling the crowd into action in a mottled Mancunian language only he can understand, he seems to take the rumours of Oasis's decline as a personal affront, which he is here to dash.

By the time "What's the Story (Morning Glory)'' crashes into the set, it is hard to argue with him. The band's dip in form and fortune, far from crossing them, has pressured them into a furious, regained relevance I thought was far beyond them now.

The encore, as exciting as anything played at Knebworth, confirms this. "Don't Look Back in Anger'', Noel's greatest song, reminds me of why I loved Oasis in the first place. "Please don't put your faith in the hands of a rock'n' roll band – they'll throw it all away,'' Noel sings tentatively. But as the crowd sing along to this classic about why rock'n' roll matters, democratically turning to each other to lead the choruses, my faith, against all my expectations, is restored.

"Some Might Say'' follows, with this introduction from Liam: "Some might say ... that English rock'n'roll is dead. Well, it isn't while I'm alive.'' Before this gig, that would have sounded ridiculous. But tonight, it again makes perfect sense. Oasis have been ambitious, inclusive and inspirational: the Greatest British Rock'n'Roll Band again after all.