Long ago, regiments were recruited by the ‘Lord of The Major’ to fight for King and Country (there being no ‘standing army’ at the time). As they were local men they had regiment names that showed from where they came.
They also had their private churches, the ‘Buffs’ chapel is in Canterbury Cathedral. As an aside there is a saying, allegedly, from the Crimean war ” Forward The Buffs’ regarding a terrible advance into the enemy fire. I personally believe this saying may be attributable to a previous battle.