Dr Ian Plummer

http://www.oxfordcroquet.com/laws/6th/51.asp
Oxford Croquet

51. MISCELLANEOUS LAWS OF CONDUCT

1. INTERRUPTING THE STRIKER The adversary must not interrupt, distract, interfere with or offer advice to the striker except to forestall play in accordance with Law 23. If he does so, Law 55 may apply and the striker may take advantage of any such advice.
2. PRESENCE ON COURT The adversary must not ordinarily remain on the court when the striker is playing or move onto it until the striker's turn has ended and, in handicap play, until the striker has indicated that he does not intend to play a half-bisque or bisque.