It was singing the old song ‘Cherry Ripe’, a common enough thing which I had chiefly known from barrel-organs.  But heard in the scented moonlight it seemed to hold all the lingering magic of an elder England and of this hallowed countryside.  I stepped inside the garden bounds and saw the head of the girl Mary.

She was conscious of my presence, for she turned towards me.

‘I was coming to look for you,’ she said, ’now that the house is quiet.  I have something to say to you, General Hannay.’

She knew my name and must be somehow in the business.  The thought entranced me.

‘Thank God I can speak to you freely,’ I cried.  ’Who and what are you—­living in that house in that kind of company?’

‘My good aunts!’ She laughed softly.  ’They talk a great deal about their souls, but they really mean their nerves.  Why, they are what you call my camouflage, and a very good one too.’

‘And that cadaverous young prig?’

’Poor Launcelot!  Yes—­camouflage too—­perhaps something a little more.  You must not judge him too harshly.’

‘But . . . but—­’ I did not know how to put it, and stammered in my eagerness.  ’How can I tell that you are the right person for me to speak to?  You see I am under orders, and I have got none about you.’

‘I will give You Proof,’ she said.  ’Three days ago Sir Walter Bullivant and Mr Macgillivray told you to come here tonight and to wait here for further instructions.  You met them in the little smoking-room at the back of the Rota Club.  You were bidden take the name of Cornelius Brand, and turn yourself from a successful general into a pacifist South African engineer.  Is that correct?’

‘Perfectly.’

’You have been restless all evening looking for the messenger to give you these instructions.  Set your mind at ease.  No messenger is coming.  You will get your orders from me.’

‘I could not take them from a more welcome source,’ I said.

’Very prettily put.  If you want further credentials I can tell you much about your own doings in the past three years.  I can explain to you who don’t need the explanation, every step in the business of the Black Stone.  I think I could draw a pretty accurate map of your journey to Erzerum.  You have a letter from Peter Pienaar in your pocket—­I can tell you its contents.  Are you willing to trust me?’

‘With all my heart,’ I said.

’Good.  Then my first order will try you pretty hard.  For I have no orders to give you except to bid you go and steep yourself in a particular kind of life.  Your first duty is to get “atmosphere”, as your friend Peter used to say.  Oh, I will tell you where to go and how to behave.  But I can’t bid you do anything, only live idly with open eyes and ears till you have got the “feel” of the situation.’

She stopped and laid a hand on my arm.