Conversation so far:
what was the reform about?
By the 1860s it was recognised that musical standards in the choir needed improvement
what kind of improvement did the musical standards in the choir needed?
the Choral Service has suffered mutilation in every place where it is retained. King's College has reduced the original number of its Conduct Chaplains from three to one
what other reforms happened Choir of King's College, Cambridge?
mongst the lay clerks, whose duties were at this time divided by also singing at Trinity, indiscipline and absenteeism were common.

Question: who or what was Trinity
Self-contained rewrite: who or what was Trinity in the choir of King's College cambridge?