Fly-half Mark Mapletoft was London Irish's undoubted star, with the bald-headed pivot contributing 17 valuable points through one try, three conversions and two penalties.
Mapletoft was one of three try-scorers for the Exiles, who outscored their hosts by three tries to two in the final analysis, all three of their tries coming within the first 22 minutes of the match.
The Exiles scored a massive 24 points in the first half, but were simply unable to break down the more stubborn Northampton defence in the second half, with the home side outscoring their visitors by 9-6 in the second stanza.
Like London Irish, most of Northampton's points came from the boot of their fly-half, in this case former Wallaby Shane Drahm, who also got on the scoresheet in three ways – through one try, one conversion and four penalties.
For Northampton Saints:Tries: Drahm, RobinsonCon: DrahmPens: Drahm 4
For London Irish:Tries: Sackey, Bishop, MapletoftCons: Mapletoft 3Pens: Mapletoft 2, Everitt