On 22 July 1914, the Austro-Hungarian Ambassador to the United Kingdom Albert Count Mensdorff (pictured) sent a coded private telegram to the Austro-Hungarian Minister of Foreign Affairs Leopold Count Berchtold. In his telegram, Mensdorff refers to the Austro-Hungarian ultimatum to Serbia.
Count Mensdorff to Count Berchtold. London, 22 July 1914.
[The British Foreign Secretary] Sir Edward Grey has just asked me by telephone to go and see him at 15:00 tomorrow.
It is just possible that he has something to say to me on the subject of our forthcoming step in Belgrade.
Would your Excellency authorise me, eventually, to communicate the official decree tomorrow, Thursday afternoon, instead of Friday, asking the Foreign Secretary to consider it as strictly private until Friday?
I beg for an immediate answer by wire.
Source: 1919 Austro-Hungarian Red Book, with minor edits.