sentences:  He also joined the Russian Social Democratic and Labour Party as a British member in 1901, siding with the Bolshevik faction against the Mensheviks and becoming a close comrade of Lenin, who often stayed at Rothstein's house on Clapton Square in the Hackney area of London.Rothstein published "Egypt's Ruin" (1910), an analysis of Egypt's systematic exploitation by the British after the occupation, evidenced by British government documents and correspondent reports from London newspapers regarding Egypt.Although Rothstein was a convinced opponent of World War I, he worked for the Foreign and Commonwealth Office and the British War Office as a Russian translator and interpreter.