steganography, n., uncountable: The practice of hiding messages, so that the presence of the message itself is hidden, often by writing them in places where they may not be found. (Wiktionary definition 1)
That should be a sufficient clue for the puzzle which the Choirmaster included in today’s order for service:
Order of Service for Sexagesima Sunday 2013. Click to embiggen (and to rotate properly).
If you really need another clue, perhaps the Order of Service cover will help:
Cover of the Order of Service for Sexagesima Sunday 2013. Click to embiggen.
