The Royal Wedding: secrets of the guest list - Telegraph: "Prince William’s wedding will be the most sought-after invitation of 2011. But neither the Prince of Wales nor the Middletons will be sending out the cards. This will be done by the Lord Chamberlain’s Office, which will consult the young couple and look back in files to see which public figures should be invited, according to protocol.
Since Prince William will one day be King, the guest list is not entirely his prerogative. The Queen and the Prince of Wales will have a say, and certain government departments may be consulted, most particularly the Protocol Department of the Foreign Office. Lord and Lady Spencer, for instance, were allowed only 30 personal guests at St Paul’s Cathedral in 1981."