The article studies the U. K. foreign policy towards German question, that became topical again in the late 1980s. New declassified archive documents of the Foreign Office are being introduced in progress. Volume “Documents on British Policy Overseas: German Unification 1989—1990” include materials of British ministry previously closed to public access. By now it remains the most important available source of information about decision-making mechanism in the U. K. in 1989—1990. Also relevant became the interview with Lord Charles Powell, who was Margaret Thatcher`s private secretary in 1989—1990 and was in the middle of British political life during that period. The article considers all main stages of German Unification at the end of 20th century. In this work the author studies how British government was involved in the process of finding the way to solve one of the most difficult problems of last century. The main focus of the research concentrates on the making of new European security system, analyzing the U. K. versions, their relevance and expediency. In the conclusion it is being revealed how much Britain contributed to the solution of German problem, what was the omissions and repercussions of the events that took place more than 25 years ago.