I have to agree with Orange Baseball growing up and playing sports for Pinkerton the one game we always looked for regardless of the sport was when we played the Lancers......as mentioned the records can be thrown out the window when these two play each other, and from Freshman to Varsity there is no love between the Astros and Lancers. Even as a spectator for other sports you knew too boo Londonderry. Some of the most competitive and intense games I've played in and watched were against Londonderry.
I think the Nashua schools are close but as mentioned above those guys play together growing up and have friendships with each other, but it was very rare for anyone from Derry or Londonderry to play together in High School sports.