The stage was set for Fijian giant Nemani Nadolo but it was rookie flanker Tommy Reffell who stole the show in Leicester’s first victory since the restart.
While 21st 7lb Nadolo showed flashes of his cult hero potential on the wing, the Premiership’s new breakdown interpretations made this a day for the flankers.
Reffell, the 21-year-old Welshman, led the Tigers’ breakdown charge against the Exiles.
Leicester have made 27 personnel changes in the first three rounds and returning No 10 George Ford kicked eight points off the back of Reffell’s workmanship.
Despite threatening breaks by Curtis Rona and Ollie Hassell-Collins, Leicester’s first-half defence held firm and they led through a try from David Williams.
Nadolo almost capped off his debut with a score of his own but, like Tom Youngs and Reffell, his try was ruled out.
‘It’s been six months since my last game — I was blowing seagulls!’ said Nadolo. ‘I was proud to play 80 minutes.’
Nadolo shifted to No 8 after Callum Green was sinbinned, and London Irish turned up the pressure with the extra man.
The visitors finally breached the Tigers’ tryline through Ben Meehan after 61 minutes but Leicester held on for their first victory since March.