Deciding what kind of media to use for this brief is difficult. It has to be accessible to core audience in both indoor, outdoor, online and event situations.
I think some kind of mobile media or location based service will be best suited to this brief.

GPS - no good as does not work indoors
SMS - a possibility but it is not a very original concept for brand promotion
QR codeds - a likely possibility

discuss with client the possibility of using QR Codes for the brief
First client meeting to be held today with Simon Pope