I closed the door and returned to my seat.  Then I reached for the telephone and put the receiver to my ear.

“What an extraordinary thing!” said a voice.  “And you’ve no idea whose it was?”

“Not the slightest,” came the reply.  There was a musical note in the girlish tone that would have attracted any one.  “There it was, on the top of the car, when we got to the Berkeley.  It wasn’t such a bad hat, either.”

“Excuse me,” said I.  “It was a jolly good hat.”

A long tense silence followed my interruption.  At length—­

“I say, are you there, Dot?”

“Yes,” came the reply in an excited whisper.  “Who was that speaking?”

“I’ve not the faintest idea,” rejoined the first voice I had heard.  “Somebody must have got on to our line.  I expect——­”

A familiar explosion severed the sentence with the clean efficiency of the guillotine.

“Isn’t that sickening?” said I.  “Now we shall never know what her theory was.”

“It’s all your fault, whoever you are.  If you hadn’t butted in——­”

“I don’t know what you mean,” I retorted.  “I was ushered into your presence, so to speak, by la force majeure.  French.  Very difficult.”

“Well, when you heard us talking, you ought to have got off the line.”

“I should have, if you hadn’t started disparaging my headgear.  I repeat, it was a hat of unusual elegance.  It had a personality of its own.”

“But it wasn’t your hat we were discussing.”

I sighed.

“All right,” I said wearily.  “It wasn’t.  Have it your own way.  Some other fool followed a silver-grey Homburg twice round the Park this morning.  Some other fool——­”

A little gasp interrupted me.

“But how did you know my number?”

“I didn’t.  I don’t.  I never could have been about to should.  Negatives all the way.  It’s just chance, my dear.  Chance with a Capital J—­I mean C. D’you mind if I smoke?”

Her reply was preceded by a refreshing gurgle.

“Not at all,” said my lady.  “D’you mean to say you chased us all that way?”

“Further.  And if it hadn’t been for that fire-engine——­”

“I remember.  Wilkins turned down a side-street.”

“Exactly.”

“What a shame.  Well, if you go to your hatter’s you’ll get it again.”

“Your ingenuity is only equalled by your consideration.  Isn’t that neatly put?  You see, I’m writing a letter to The Observer, and, when I get going, I can just say things like that one after another.”

“How wonderful.  But I’m afraid I’m interrupting you, and I shouldn’t like to deprive Humanity——­”

“Your name,” said I, “is Dot.  But I shall call you Mockery.  And if you’re half as sweet as you sound——­”

“Good-bye.”

I protested earnestly.

“Please don’t say that.  We’ve only just met.  Besides ... why was Clapham Common?”