Saracens had triumphed 45-24 in their Pool C encounter at StoneX Stadium in Round 4, but Irish exacted their revenge in the Gallagher Premiership at Brentford Community Stadium.

Benhard Janse van Rensburg scored two tries for the hosts before Adam Coleman – who was later sent off – and Ollie Hassell-Collins went over, but efforts from Tom Woolstencroft, Rotimi Segun and Nick Tompkins plus 15 points from Alex Lozowski looked to have won it for Saracens.

However, Jackson, who had already kicked nine points, stepped up to slot a penalty on 80 minutes to snatch victory for Irish.

Saturday’s other Premiership action saw three sides dropping into the EPCR Challenge Cup Round of 16 – Wasps, Bath Rugby and Northampton Saints – all fall to defeats.

Wasps scored tries through Tom Willis, Sam Spink and Jeff Toomaga-Allen but were beaten 29-24 at Harlequins.

Northampton crossed through Juarno Augustus, Alex Coles and Alex Mitchell as they lost 22-21 at home to Sale Sharks, while Bath went down 24-20 to Leicester Tigers at The Recreation Ground despite scores from Will Muir, Max Ojomoh and Josh Bayliss.

In the United Rugby Championship, tries from Ollie Smith and Jack Dempsey saw Glasgow Warriors beat Benetton Rugby 13-3 at Scotstoun Stadium, their fifth win in a row in the competition.

In the TOP 14, RC Toulon came out on top in an all-EPCR Challenge Cup encounter with USAP, triumphing 29-18 at home thanks to tries from Julien Hériteau, Facundo Isa, Gervais Cordin and Jules Danglot. Bautista Delguy dotted down for USAP, as did Tristan Tedder, who also kicked eight points.

In another all-Challenge Cup affair, now that they have dropped into the competition, Castres Olympique edged past Lyon 19-17 at home. Thomas Combezou crossed and Benjamin Urdapilleta kicked 14 points for Castres, while Jérôme Rey and Clément Laporte notched tries for Lyon.

Elsewhere, Section Paloise stunned reigning European champions Stade Toulousain 27-22 at Stade du Hameau. Steve Cummins, Tumua Manu and Elliott Roudil grabbed the hosts’ tries.

Saïd Hirèche went over and Enzo Herve kicked 11 points as CA Brive drew 16-16 at home to last season’s Challenge Cup winners, Montpellier Hérault Rugby, while John Dyer, Gavin Stark and James Cronin registered tries as Biarritz Olympique crashed 65-19 at Stade Français Paris.

Fly-half Paddy Jackson kicked a last-gasp penalty to lead London Irish to a 32-30 derby win over Saracens on Saturday and so avenge their EPCR Challenge Cup loss at their London rivals last month.