"...His Majesty's Ambassador at Tokyo has been instructed to inform the Imperial Japanese Government in the name of His Majesty's Government in the United Kingdom that a state of war exists between our two countries.
I have the honour to be, with high consideration,
Sir,
Your obedient servant,
Winston S. Churchill".
Some people did not like this ceremonial style. But after all when you have to kill a man it costs nothing to be polite.