Benjamin Britten’s “War Requiem,” isn’t often performed, largely because of its massive personnel requirements – a full orchestra, a separate chamber orchestra, plus several choirs and vocal soloists – but this week, the Minnesota Orchestra and St. Paul Chamber Orchestra will combine for the first time in decades to bring the anti-war opus to life. And the music won’t be the only star: as luck would have it, a 93-year-old musician who played in the Requiem’s emotional premiere in Coventry, England lives three hours from the Twin Cities, and is being brought in to attend the concert and speak to the audience about the impact Britten’s work had on a shattered post-war British public.