"We're definitely disappointed," said Hodgson. "It's probably one of the most gutting feelings we've had as a team for a long time.
"It was a game we should have been in control of. We've let it slip away. A lot of what we did do was what we set out to do as far as the game plan was concerned.
"But there was an inability to hold on to the ball, we weren't as efficient as we should have been at ruck time and we sometimes gave away penalties in the wrong positions — there's probably quite a few things you could list.
"There were some home truths spoken in the changing room, so hopefully we can have a reaction, not just next week but for our season in general."
At least Irish know they have the beating of next weekend's high-profile opponents. Irish began their European campaign with the biggest of bangs as they shocked the holders 12-9 on their own patch.
And while a similar scoreline wouldn't be enough to win the group, it could well guarantee Irish a quarter-final place in the competition as one of two best runners-up.
Hodgson has dismissed all talk of a four-try haul and insisted that victory will be the only thing on their minds during one of the most-talked about games in the club's history.
"Leinster probably played a little bit below par when we played them over there," he said. "We'll just be looking to put in a performance that will give us a chance to win and then what will be will be after that. We'll embrace the challenge and we're looking forward to it.
"London Irish still is a special group of players. We've got guys from all over the world and we've got some great personalities.
"So we won't dwell on this result too long but we'll definitely go through the game with a fine tooth comb to try and put things right, starting with next week."
