On 27 July, Sir Edward Grey, the British Foreign Secretary, detailed his proposal to prevent the escalation of the crisis between Serbia and Austria-Hungary to the Russian Ambassador in London.
Russian Ambassador to the United Kindgom to Russian Minister for Foreign Affairs. London, 27 July 1914.
Grey has just informed the German Ambassador, who came to question him as to the possibility of taking action at St. Petersburg, that such action ought rather to be taken at Vienna, and that the Berlin Cabinet were the best qualified to do so. Grey also pointed out that the Servian reply to the Austrian note had exceeded anything that could have been expected in moderation and in its spirit of conciliation. Grey added that he had therefore come to the conclusion that Russia must have advised Belgrade to return a moderate reply, and that he thought the Servian reply could form the basis of a peaceful and acceptable solution of the question.
In these circumstances, continued Grey, if Austria were to begin hostilities in spite of that reply, she would prove her intention of crushing Servia. Looked at in this light, the question might give rise to a situation which might lead to a war in which all the Powers would be involved.
Grey finally declared that the British Government were sincerely anxious to act with the German Government as long as the preservation of peace was in question; but, in the contrary event, Great Britain reserved to herself full liberty of action.
Source: Russian Orange Book.