Hey Dan, sorry if a controller tells someone to hold at a point and doesn't specify the pattern (ie. direction, lengths of legs etc.) then the pattern must be a published pattern. If you cannot find that published pattern for whatever reason, it falls on your head to query the controller as to a description of the pattern. Saying that we didn't have it published so we held right, doesn't hold any water with me.
This all comes down to good airmanship, and for any pilots reading this that includes on first contact reporting level passing and level cleared to. It takes 3 seconds but it saves 2 more bits of RT. That is particularly aimed at the Sub-Continent airlines who's first call is always, "AirIndia XXX Hello".