Article: Independently of the method used to signify royal assent, it is the responsibility of the Clerk of the Parliaments, once the assent has been duly notified to both houses, not only to endorse the act in the name of the monarch with the formal Norman French formula, but to certify that assent has been granted. The clerk signs one authentic copy of the bill and inserts the date (in English) on which the assent was notified to the two houses after the title of the act. When an act is published, the signature of the clerk is omitted, as is the Norman French formula, should the endorsement have been made in writing. However, the date on which the assent was notified is printed in brackets.

Now answer this question: Who writes the formal Norman French formula on passed acts?
Clerk of the Parliaments