(Due to arrive Melbourne-9.1.26)
My dear P.M.,
I do not want to continue to bother you by sending all this Communist material  addressed personally to you, so that you are practically obliged to read it before passing it to Major Jones.  Could I not address it all, properly sealed, to Jones c/o Henderson  at your office, and let Jones extract anything of immediate interest or importance for you.
It is all of extreme secrecy as you know, especially the intercepted material. I do not want to suggest anything that would make for any chance of leakage. 
I am, Yours sincerely, R. G. CASEY