In a dramatic finish, Paul Burke added the points to a Tony Diprose try to edge Harlequins 27-26 ahead. However, Everitt tagged on two penalties to send London Irish back to Twickenham for the first time since 1980.
It was a remarkable game in that London irish led 26 nil at one stage and then 26-10 at half time. Harlequins continued to eat away at the lead and it seemed they had completed a remarkable come-back when Ireland A International Burke converted his side's third try.
But not for the first time this season, Everitt combined deadly accuracy with nerves of steel to earn his side a marvellous victory