Played in Brass band for 35 years before learning guitar
The same pieces you heard being played were probably the compulsory competition piece , the bands would be being judged on that as well as the pieces of their own choice. Its music to very high standard
I was on a work camp course once and heard a cornet practising i the first aid block and asked the guy who was o the same course as me if i could try his cornet. H had the music fo "Under the Double Eagle" out to play , I played it thro and his comment was " aye sounds like it but its nowhere near whats actually written there " I took the first part as complement as i was a tuba player, and the sceond part as constuctive criticism as i was playing from memory and ear and not from the actual music, he was a senior competition band 1st cornet and a great musucian.