The term “late period” isn’t really appropriate in Brian’s case, given that the composer wrote 26 of his 32 symphonies between the ages of 72 (in 1948) and his death at aged 96 in 1972. The last ten span the final four years of Brian’s composing life, between 1964 and 1968. Within them, numbers 22-24, in particular form a concentrated and related group. Written between December 1964 and August 1965, they all have something of a martial sound and share a concern for march-rhythms, changeable moods and developing variation.
Symphony No 22 "Symphonia Brevis" (1964-5, but first performed in 1971) is Brian’s shortest symphony (at just nine minutes long) and one of the most tightly organized, with the dense polyphony of the opening maestoso, leading to a ghostly, nocturnal march, calm but uneasy.
Symphony No 23 (1965, first performed 1973) is another two movement work, Brian considered calling it “Symphonia grandis”. Like its predecessor, includes martial elements (in the opening allegro and prior to the conclusion). “Eerie, belligerent and seethes with incident” (Rob Barnett).
Symphony No 24 in D major (1965, first performed 1973) has just one movement of 18 minutes length, though it's divided into three sections of widely varying mood. The work closes with a restful, optimistic adagio.