As speaker of the House of Commons, however, Bercow is one of three people who has the authority to block visiting figures from doing this.
Who are the others I wonder. Prime Minster probably is one of them, but who is the other? I doubt Parliament would stand for the Queen being able to do this.
The 3 people who can are named in this article mate:-
^ The other 2 are Lords Speaker Lord Fowler, and the Great Lord Chamberlain - an official appointed/chosen by The Queen (if I remember correctly)