In January 1939, whilst working at the British/U.S.A. intelligence section of the German War Ministry at the German Embassy in London, Schwerin made a clandestine personal approach to the British Government, suggesting that if it abandoned its policy of appeasement towards the Third Reich, and instead moved to a stance of open military opposition towards its escalating aggression in central Europe, this would provide a rallying point and catalyst for elements in the German military who were at that time considering launching a coup d'etat against the National Socialist government of Adolf Hitler. At a dinner party in Marylebone hosted by Admiral Sir Aubrey Smith, Schwerin met James Stuart, representing the British Government, Admiral John Godfrey, head of naval intelligence, and General Sir James Marshall-Cornwall, Director-General of air and coastal defence, to warn them of Hitler's intention to invade Poland. Along with the suggestion that Great Britain's and Germany's best interests would be served by Neville Chamberlain being replaced as Prime Minister by Winston Churchill, Schwerin advocated that pressure for an internal military coup by anti-Nazi elements of the Wehrmacht, of which he was aware, could be induced by the deployment of a squadron of Royal Navy battleships taking up a hostile position off Germany's Northern shore in the Baltic Sea, and by the Royal Air Force moving elements of its Bomber Command to a pre-battle theatre station in French airfields, as a means of indicating the British Empire's ultimate willingness for a confrontation with the Nazis. This politico-military strategy was communicated to Chamberlain but was rejected as being too aggressive at that point as a way of dealing with the gathering menace of the Third Reich. However, Schwerin's representations to the British Government may have contributed to its collective assessments which were ongoing at that time as to how to deal with Adolf Hitler, and to the decision to make a stand on the Polish border eight months later rather than somewhere else. Frank Roberts, an official in the Foreign Office's German Department who also dealt with the issue, light-heartedly - in spite of the risk that Schwerin had taken in making such a move on the eve of war, which would constitute high treason and a capital crime in the Third Reich's jurisdiction if it was discovered - dismissed the subject of Schwerin's approaches as being an internal matter for the German high command. In April 1939 Schwerin was promoted to the rank of lieutenant colonel.