NSB will be in action in the England Rugby Under-15 Schools Cup final on Thursday afternoon (kick-off 12.30pm).
They will face Wellington College in the showpiece.
The NSB players enjoyed a shirt presentation with Saints star and former NSB pupil Courtney Lawes in the build-up to the game.
And NSB director of sport Jamie Wilcock said: “There are students in this Under-15 age group who hope to one day emulate the achievements of their sporting heroes.
"Several of them have the talent to do so and for 22 that prospect will feel all the more achievable when they run out onto the pitch at Twickenham on Thursday."