Free of the frustrations experienced during England's failed World Cup campaign, Delon Armitage and Shontayne Hape rediscovered the art of enjoyment as Irish collected a maximum five points.
Armitage weighed in with a try and a cracking performance while Hape, making his debut after signing from Bath in the summer, carved out a try for Dan Bowden with a typical bullocking break.
Starting fly-half Steven Shingler added three penalties and a conversion before Bowden replaced him on 54 minutes and increased the quality of the Irish attack. He also scored a try, conversion, penalty and drop-goal.
Newcastle, fielding a young XV, turned up awash with fizz and ambition, twice led and scored three good tries yet left the Madejski Stadium empty handed whereas Irish now have six points from their two LV=Cup ties before returning to Aviva Premiership duties next weekend.
"We take this competition very seriously," said Irish head coach Toby Booth. "It's an opportunity for Irish to win silverware and a tremendous opportunity to qualify for Europe even before the Premiership is completed."
Owen Farrell took the starring honours for Saracens at Vicarage Road as they sank Exeter 43-20.
Farrell kicked five penalties and converted his own try as well as those scored by Powell, Penny and Vyvyan. Exeter replied with tries by Bentley and Dorrian while Steenson added two penalties and two conversions.
Scarlets made swift work of Blues in Cardiff, romping home 30-3 with tries by Warren, Pugh, Mayhill and Murphy. Thomas kicked two penalties and two conversions while Cardiff's sole score was a Patchell penalty.
London Irish: Tries Thompstone (2), Armitage, Bowden. Conversions Shingler, Bowden. Penalties Shingler (3), Bowden.
Newcastle: Tries Goosen, Helleur, Graham. Conversion Manning. Penalties Manning (2).
London Irish: D Armitage; A Watson, J Joseph, S Hape, A Thompstone; S Shingler, R Samson; M Lahiff, J Buckland, P Ion, N Kennedy (c), B Evans, D Danaher, R Thorpe, J Gibson.
Newcastle: G Goosen; R Sheriffe, L Eves, J Helleur, A Tait; J Manning, C Pilgrim; D Fearn, M Mayhew, J Hall, G Townson, A van der Heijden, M Wilson, A Hogg (c), R Pennycook.
Referee: Dean Richards.