Please seek interview with [German] Minister for Foreign Affairs at 9 a.m. today, Sunday, or, if he cannot see you then, arrange to convey at that time to representative of German Government the following communication:
"In the communication which I had the honour to make to you on 1st September I informed you, on the instructions of His Majesty's Principal Secretary of State for Foreign Affairs, that, unless the German Government were prepared to give His Majesty's Government in the United Kingdom satisfactory assurances that the German Government had suspended all aggressive action against Poland and were prepared promptly to withdraw their forces from Polish Territory, His Majesty's Government in the United Kingdom would, without hesitation, fulfill their obligations to Poland.
"Although this communication was made more than twenty-four hours ago, no reply has been received but German attacks upon Poland have been continued and intensified. I have accordingly the honour to inform you that, unless not later than 11 a.m., British Summer Time, today 3rd September, satisfactory assurances to the above effect have been given by the German Government and have reached His Majesty's Government in London, a state of war will exist between the two countries as from that hour."
If the assurance referred to in the above communication is received, you should inform me by any means at your disposal before 11 a.m. today 3rd September. If no such assurance is received here by 11 a.m., we shall inform the German representative that a state of war exists as from that hour.
G. A. Kertesz, Documents in the Political History of the European Continent 1815–1939 (Oxford, UK: Clarendon Press, 1968), 486–487. .