A sexton is a church officer charged with the maintenance of church buildings and/or the surrounding graveyard. The word derives from the Medieval Latin word sacristanus meaning ‘custodian of sacred objects’. Traditionally, the sexton’s role included the digging of graves.
The word clerk is derived from cleric. In medieval times the clergy were one of the few groups who could read, and were therefore often employed to do bookkeeping and similar work. Church clerks are responsible for minute-keeping, correspondence and other documentation.
In a small parish, it would not be unusual to combine the offices of clerk and sexton.