I would say that the sense of urgency would be for warning that Hitler had a plan to invade Britain since such an event would be extremely serious and would require all the armed force to be marshalled to prevent this and to fight the Nazis in the air, on the ground and at sea to repel them and show the resolve of the people of Britain.
<span>The statement that "We are told that Herr Hitler has a plan for invading the British Isles" certainly creates the greatest tone of urgency of these statements. By planting a stake in the ground and making it clear that the homeland is in peril, Churchill moves to spur the British people to immediate action.</span>