Naturally, I would not trouble you in this way if the cause was not vital to the ends of justice.

Whether or not you decide to keep this appointment, I have every confidence that you will respect my wish that _no one_, other than yourself, shall be informed of my identity.

But I believe you will be wise, and come.
I am, Yours faithfully, J.L.

WINTER, Chief Inspector, C.I.D., Scotland Yard, S.W.
A card was inclosed, as a sort of credential.

But, somehow, it was not needed.