Knight and Clergy
A clergyman of the Church of England, if appointed a knight of one of the Orders of Chivalry, does not receive the accolade, and is thus not accorded the prefix 'Sir' before his name, but he places the appropriate letters of the Order concerned after his name, eg:
The Rt Rev the Lord Bishop of Sevenoaks, KCVO.
The wife of a priest so honoured is not styled or addressed 'Lady', unless of course she is already entitled to such designation.
Clergy of other Churches may receive the accolade and thus use the title 'Sir'.
If a Knight of an Order of Chivalry is subsequently ordained a clergyman of the Church of England, he has no need to relinquish the prefix of 'Sir', eg The Rev Sir Herbert Andrew, KCMG, CB.