In a convention dating back to the 17th Century, when Charles I relations with Parliament were icy to say the least, the Monarch’s visit to the Palace of Westminster only takes place when a ‘hostage’ has been handed over from the House of Commons to guarantee her safety.
This ‘honour’ goes to a senior Member of the Government Whips’ Office who, by convention, is the Vice-Chamberlain of the Royal Household. The current post-holder is Greg Knight, the MP for East Yorkshire. And so, on the morning of the State Opening, he will make his way to Buckingham Palace to be symbolically locked up until the Queen returns.
So far no monarch or MP has come to any harm, and it is unlikely that Greg Knight will be in any real danger. You can read our preview of the Queen's speech here.