Several of my capable assistants then took over the task of finding out all that was known regarding the house in Lembridge Square. Forty-eight hours later I had a full report. I learned that the man in whose room the parrot lived was one of the mysterious band who foregathered to meet Kristensten in the empty house in Harrington Street. He was then dressed as a special constable, a part which, by the way, he had no right whatever to play. He bore the thoroughly English name of Mostyn Brown, and was in business in the City as the agent of a Manchester firm of cotton merchants. Apart from the fact of his presence that night in Harrington Street, nothing that the most exhaustive inquiries revealed suggested in the smallest degree any association with agents of the enemy. To all appearances he was a perfectly respectable City man, in no way different from thousands of others. But—there was a very big but: what was his business in the dead of night in an empty house in the West End in company of a suspected German spy?
A few days later the men who were keeping the houses in Lembridge Square and Hereford Road under surveillance sent me a strange report, which set me thinking deeply. By some means—whether he suspected he was being watched or whether a lucky chance favoured him, we never knew—Blind Heinrich managed to elude the unwearying vigilance of Madame Gabrielle and arrived alone, evidently in a hurry, at Westbourne Grove. Here he hailed a taxi and was driven to Waterloo Station. There at the booking-office on the loop-line side he had met a short, fat man, to whom, after a brief conversation, he handed a bottle wrapped in white paper. They remained in conversation a few minutes longer and then parted. The fat man was followed to the tube railway and thence to King’s Cross, where he had bought a ticket for Peterborough, and left by the five-thirty express.
Why Peterborough, I wondered? There were certainly no facilities there for anyone engaged in Germany’s nefarious work. But attached to the report was a snapshot—taken secretly, of course—which showed me at once that the little fat man was apparently a sailor, “camouflaged” hastily in a badly fitting overcoat and a cloth cap. That gave me a further clue. I took down a Bradshaw, and, glancing at the train by which the little fat man had travelled, made an interesting discovery. It was the Newcastle express. I began to see why the mysterious little man had booked to Peterborough. That afternoon I ascertained that the parrot’s cage in the house in Lembridge Square sported a broad ribbon of yellow satin. At midnight I rang up Hecq at his house at St. Germain, and asked him to send Aubert the detective over at once.
An hour after midnight came another air-raid alarm—the second to coincide with the appearance of the yellow ribbon.
Now one coincidence of this kind may mean nothing. Two begin to be suspicious. A third is convincing. I found my suspicions deepening into certainty.
Directly the air-raid warning was given, our watchers in Harrington Street were keenly on the alert, but, though they watched all night, there was no meeting of the mysterious men in the empty house. I guessed the reason. The raiders were again driven back before they could reach the Metropolis, and, therefore, there was no news to be gathered for transmission to the authorities in Berlin. Everything now pointed with increasing certainty to the house in Lembridge Square as a focus of enemy activity.
Directly the “All clear” had been sounded over the London area, Heinrich left Hereford Road, and, according to Madame Gabrielle’s report to me, hurried round to the house of the grey parrot. He remained there about half an hour, and then retraced his steps home in the waning moonlight.
Thus mystery followed mystery. What was the meaning of the various coloured bows on the parrot’s cage? For that they had a very definite meaning I no longer doubted. It seemed, indeed, tolerably clear that the yellow ribbon betokened a coming raid. And evidently the half-blind old musician was a close friend of the manufacturers’ agent. But who, in reality, was the mysterious Mostyn Brown, and, if he were indeed an enemy agent, how had he managed to elude the close watch that had been set upon him?
It had struck me that the house which sheltered the grey parrot might conceivably conceal a wireless plant of sufficient power to convey a message to a submarine lurking off the coast. Such a plant need not be a conspicuous affair. But one of my agents, posing as an official of the Metropolitan Water Board, had been able to negative the suggestion, and I confess I found myself still hopelessly puzzled as to the means by which information of the damage done by the raiding aircraft was so speedily and so accurately conveyed to the enemy.
By this time Aubert had arrived from Paris, and had taken an obscure lodging in Chessington Street, a dingy thoroughfare off the Euston Road. By appointment I met him late one night at the corner of Grey’s Inn Road and Holborn, and, having explained to him briefly what had occurred, told him to hold himself in readiness for instant action.