But Richards reserved special praise for the marauding Chris Hala'ufia and admitted he faces a selection dilemma with England international Nick Easter returning to full fitness in the coming days.
"That's the best we have played all season," said Richards, who guided Quins back into the Premiership at the first time of asking last season. "We looked good and took our chances very well.
"Our execution was absolutely outstanding and defensively we were very strong. We've been working on our defence and it really showed.
"Chris Hala'ufia had a storming game and it will be a real selection problem when Nick Easter comes back to fitness.
"Andrew Mehrtens also played well and it's nice to see him back in contention. It makes a massive difference to have a player with such experience in your ranks.
"We have a motivated group of guys at this club, with a lot of youth and exuberance. We're turning the tables and a win was very important."
The result now leaves Richards' side hauling themselves to within touching distance of a surprise play-off push.
Two quick tries before and after the break ended London Irish's hopes and inflicted only a second defeat in seven games on the Exiles.
As Quins took their foot off the gas, Irish staged a late rally with Kieran Howard scoring but the Exiles' director of rugby Brian Smith admitted it was too little too late.
"We're all scratching our heads to see where it went wrong," he said. "The first-half double try was a kick in the teeth but we gave ourselves a shot at the game at half-time.
"The period after the break was crucial and we got rolled over. We needed to score first but we got blown away. They dominated the collision and were determined to fight for the ball on the floor.
"They slowed us down and that frustrated us. We couldn't execute at the end despite being on their line for pretty much the last 20 minutes.
"We've now got two games left and we have to pick ourselves up and bounce back and quick."