Irish celebrations seeped into the Guinness Premiership on Sunday, with the Exiles coming from behind to secure a 32-27 victory over Northampton at the Madejeski Stadium.
It was end-to-end stuff with from Tom Homer kicking eight from eight on his way to 22 points.
Northampton got the game off to a breathtaking start, producing a try of stunning quality in the second minute.
Mike Catt kicked deep into the Northampton 22 but the outside-half missed his follow-up tackle on Ben Foden, allowing the visitors' full-back to set Saints in motion.
They swiftly moved the ball to get into the Irish half where James Downey made a telling contribution with a change of direction and a powerful run from which Bruce Reihana outflanked the defence to score in the corner. Former Irish favourite Barry Everitt kicked the goal from the touchline.
Irish soon responded with a sustained period of pressure.
Northampton lock Courtney Lawes was sin-binned as early as the sixth minute and Irish took full advantage when Adam Thompstone was able to force his way through Foden's good tackling attempt to score. Homer converted and five minutes later kicked a penalty to put Irish ahead.
Irish were now dominating proceedings with Steffon Armitage leading the way. He barged his way past three Northampton defenders and moments later hounded Everitt into an error to obtain possession from which Thompstone was narrowly denied another try because of a foot in touch.
Against the run of play Everitt kicked a simple penalty to level the scores at 10-10 after 27 minutes but two minutes later Homer's penalty restored home advantage.
Back came Northampton and within minutes they again took a surprise lead with a try from Roger Wilson which Everitt failed to convert before Homer hammered over a superb penalty from halfway to give the Irish a 16-15 interval advantage.
Six minutes after the restart Irish were dealt a double blow when Armitage was yellow-carded for killing the ball and from the resulting penalty
Reihana kicked the goal from halfway.
The Northampton captain repeated the dose 10 minutes later to give his side a 21-16 lead. Armitage returned but there was no immediate improvement in Irish fortunes as Reihana kicked another excellent penalty before Homer added two for the Irish to put the home side within two points of the visitors with 13 minutes to go.
Two minutes Irish then took the lead when a penalty was awarded for a high tackle by Sean Lamont and the faultless Homer made no mistake.
The intensity of the proceedings was briefly lightened by the appearance of a female streaker and the crowd had something else to cheer when with four minutes remaining referee, Sean Davey, awarded Irish the match-winning penalty try which Homer converted.
There was still further drama when Peter Richards was sin-binned and from the penalty Reihana was successful to give the visitors a most deserved bonus point, but the Exiles held on for victory.
For London Irish:
Tries: Thompstone, penalty try
Cons: Homer 2
Pens: Homer 6
For Northampton Saints:
Tries: Reihana, Wilson
Pens: Everitt, Reihana 4
Yellow card(s): Lawes (Northampton) - 6 min; Armitage (London Irish) - 46 min; Richards (London Irish), 77.
London Irish: 15 Tom Homer, 14 Adam Thompstone, 13 Elvis Seveali'i, 12 Seilala Mapusua, 11 Sailosi Tagicakibau, 10 Mike Catt (captain), 9 Paul Hodgson, 8 Chris Hala'Ufia, 7 Steffon Armitage, 6 Declan Danaher, 5 Gary Johnson, 4 James Hudson, 3 Richard Skuse, 2 Danie Coetzee, 1 Clarke Dermody.
Replacements: 16 Tonga Lea'aetoa, 17 David Paice, 18 Kieran Roche, 19 Jonathon Fisher, 20 Richard Thorpe, 21 Alfredo Lalanne, 22 Eoghan Hickey.
Northampton Saints: 15 Ben Foden, 14 Bruce Reihana (capt), 13 Joe Ansbro, 12 James Downey, 11 Sean Lamont, 10 Barry Everitt, 9 Lee Dickson, 8 Roger Wilson, 7 Neil Best, 6 Mark Easter, 5 Juandre Kruger, 4 Courtney Lawes, 3 Barry Stewart, 2 Brett Sharman, 1 Soane Tonga'uiha.
Replacements: 16 Joe Gray, 17 Tom Smith, 18 Alex Rae, 19 Mark Hopley, 20 Stephen Myler, 21 Chris Mayor, 22 Paul Diggin.
Referee: Sean Davey