State Opening of Parliament

From Tardis Wiki, the free Doctor Who reference

The State Opening of Parliament was a yearly occasion in the United Kingdom, taking place on the Eighth of November.

It would see all politicians in Britain, as well as some of the royal family (Queen included), gathering in one place for celebrations and speech-making. This caused one incarnation of the Master to try and organise a riot at the House of Parliament that day, meaning to take out the leadership of the country in one fell swoop, allowing him to take over. However, his scheme was noticed and foiled by the Sixth Doctor. (PROSE: The Radio Waves)