I hope that tomorrow we can all, wherever we are, join in expressing our grief at Diana's loss, and gratitude for her all-too-short life. It is a chance to show to the whole world the British nation united in grief and respect.

This quote is suggesting that the following day, people from across the world should come together to show their sadness for the death of Diana and thankfulness for her life. It is also saying that this could be an opportunity for British people to demonstrate to the rest of the world that they are united in their grief.