Dear Sir / Madam,
You must pardon, or I must ask you to pardon, my surreptitious departure. This course of action was factor only of an inability on my part, and under any circumstances, to say good-bye, to anyone (you will please note that I am not saying it now), I am quite simply incapable, this since birth (please don’t ever ask me about it), and so am forced to take my leave when the opportunity presents itself, regardless, I might add, of whether or not my business (if the circumstance relates to such) has been concluded. This being the case, I have taken the liberty of attaching to this document a summary of the substance to which my visit (I hope my presence has not too greatly importuned you) corresponds. Please consider me, if it should seem (I am always hesitant to loosely employ the verb “be”) appropriate, your humble servant.