Wiggy you are quite correct. It was in the speech Churchill gave at the Mansion House lunch on 10 November, 1942.
This battle was not fought for the sake of gaining positions or so many square miles of desert territory. General Alexander and General Montgomery fought it with one single idea. they meant to destroy the armed force of the enemy and to destroy it at the place where the disaster would be most far-reaching and irrecoverable.... Now this is not the end. It is not even the beginning of the end. but it is, perhaps, the end of the beginning. Henceforth Hitler's Nazis will meet equally well armed, and perhaps better armed troops. Hence forth they will have to face in many theatres of war that superiority in the air which they have so often used without mercy against other, of which they boasted all round the world, and which they intended to use as an instrument for convincing all other peoples that all resistance to them was hopeless.