Quins opened the try-scoring when wing Matt Moore breached the Exiles’ defence midway through the first half, with the boot of Paul Burke adding nine to the home side’s tally before the break.
England Sevens wing Ben Gollings was next over for Mark Evans’ strugglers, whose sluggish start to the campaign had started alarm bells ringing even at this early stage.
Four penalties from Everitt had kept the London Irish scoreboard ticking over, but a drop-goal from Quins’ versatile back Dave Slemen and a try from centre Nick Greenstock killed the game off with 12 minutes to go.
Irish did however manage a consolation score when South African wing Pieter Rossouw went over on 73 minutes, but they could not even manage a bonus point at their former stadium against their previous landlords.
The game was however played under a sombre tone, with Quins centre Will Greenwood having lost his newborn baby son Frederick.
The England star did not take the field, with the baby having passed away only 45 minutes after being born prematurely.
Both sets of players observed a minute’s silence before the match.
NEC HarlequinsTries: Moore, Gollings, GreenstockCon: SlemenPens: Burke 3DG: Slemen
London IrishTry: RossouwCon: EverittPens: Everitt 4