Letter from Michael MacWhite to Joseph P. Walshe (Dublin)
(96/43) (Secret)

I would strongly recommend that a new key for the coding of dispatches be substituted for that which has now been in existence for a couple of years. The system we employ is an old one and is not over difficult to break. It should, by this time, be well known in the countries through which our telegrams or radiograms pass.

I understand most of my colleagues here have their ciphering combination changed a couple of times in the year. For expert Black Chamber workers the change backwards or forwards is very simple unless the disposition of the key letters is also changed.