don Giorgio, you're wrong. Already since November 1940 Greece gave the duty for garissoning Crete to Britain, while a British Royal Air Force was also present, supporting the Greek operations in Albania. Add to this the material support provided by Britain.
From the moment Italy attacked Greece, Greece became by definition a British ally. Greece was no longer neutral. Greece wanted to limit the war to Italy and Greece. However as the war drew on, it became inevitable for Germany to intervene, beacuse it interfered with the plans for Barbarossa. British troops were allowed in significant numbers into Greece, after it had become absolutely obvious that Germany was preparing to invade. Indeed, it was Mussolini who already on 4 December 1940 had asked Germany for assistance against Greece, and the first plans for the German invasion began to from.
As long as the threat of a German intervention loomed above their heads, the Balkan states were very cautious and tried to remain neutral. With Germany having made clear they will stay out of the Balkans and deep inside Russia, the prospect of a re-activation of the Balkan Pact coalition plans is very realistic, particularly since Yugoslavia has her own scores to settle with Italy.