I saw her flutter a signal, and, with her arm resting naturally on the side of the basket, she rapidly tapped out a message with her nimble fingers.
“Heinrich has been with Mostyn Brown for the past two hours,” she spelt out. “He came straight from Hereford Road and went into the next house from the back.” Evidently there was some way of communication at the rear of the two houses.
I had now no time to waste, and, leaving Aubert and Madame Gabrielle to keep the necessary watch, I hurried off to Whitehall, where I was soon in deep talk with the astute and enterprising chief of the London defences, a keen officer who by sheer merit had forced himself to the very front rank in aircraft service.
“Good!” he said, when I had told him my news. “I think we shall give them a surprise to-night. Perhaps you would like to see how we work. Sit down for a bit.” And he turned to his big table, on which stood a telephone.
For the next half-hour I watched him, fascinated with his sure grasp of London’s intricate defences, and amazed, though I had thought I knew his capability, at the swiftness and decision with which he issued what to me seemed a veritable jumble of orders. To centre after centre of the aircraft defences he spoke a series of numbers, so bewildering in their speed and complexity that an enemy agent seated in the very room could not have gained a scrap of information. Even to me, familiar as I am with almost every branch of code work, it was a veritable revelation.
“I think we are ready for them now,” he said finally, wiping the perspiration from his face, and I could see that even to him the strain had been severe. How well he had done his work all England was to know the next day, though the public never even suspected the magnitude of his task.
There was now nothing to do but wait; our traps were set, and it remained to be seen whether the enemy would walk into them. I made my way to my chambers for a few hours’ rest and was soon deeply asleep.
At half-past nine Burton, my man, roused me. “The first warning has just come in,” he said.
I dressed swiftly and sat down to snatch a hasty supper, knowing well that it might be many hours before I tasted another meal.
It was exactly ten o’clock when the report of the first maroon broke the stillness, and London, with one accord, hastened to cover. Ten minutes later the streets were deserted, and a midnight hush reigned supreme. The great city seemed a city of the dead.