In a face to face situation at the end of your second / third interview.
Over the telephone after the interview process is complete.
Via email or via your Media Contacts consultant.
All of these ways will precede a formal offer letter / contract. Always keep your consultant up to date with how you feel about each position so that they can if necessary mediate on your behalf.
If you are in need of any advice or further information on the position that you have been offered then call your Media Contacts consultant. They will have the answers to any questions and will call the client to clarify matters for you. They will also advise you on salary, market values and company / career progression if asked.