Prussia now holds the upper hand on the battlefield, and at the strong request of the Berlin Government, the negotiations were set in London.
Initially, they wanted to hold it in Berlin, but the Russians did not agree, and the Tsarist Government still wanted to save some face.
The Russians were still not convinced. They insisted on having the negotiation venue in a neutral country to prove that they had not lost the war.
This was a self-deception but also involved political maneuvering. The alternative negotiation venues were Vienna and London, and now that the venue was set in London, it meant that in this round of political maneuvers, the Tsarist Government was at a disadvantage.
With a "bang", Foreign Minister Clarence Ivanov of the Russian Empire threw a cup of coffee out, splashing it all over the floor.