The sort of game that the British were playing in the Balkans in early 1941 to provide general assurances to the Yugoslav government that they would be aided if they joined the Allies. They did not want to be committed to any definite steps, which is what the Yugoslav government wanted. What they were hoping to achieve was to persuade the Yugoslavs to attack the Italian rear in Albania. They hoped that would cause an Italian collapse and would make the main Greek forces available to resist a German attack.
Anthony Eden had visited Ankara at the end of February 1941. The Turkish government seemed intent on remaining neutral and passive. General Wavell and Air Chief Marshal Longmore resisted providing any assurances to Turkey, as they seemed more of a liability than an asset (a paraphrase of the Official History). The primary reason that the British wanted a declaration of war by the Turks was to influence Yugoslavia to stay out of the Axis.
This is based on the account in Vol.II of the Official History.