Adam - the S76 is certified as a single pilot aircraft, however in the case of N Sea offshore oil support at least, the client's contracts are for 2 crew as a safety measure. So you can do a single pilot airtest, ferry flight etc but 2 pilots are required for the revenue flights. There also can be an issue with the IR - the CAA tend to like to classify the IR renewal test as either being 2-pilot (examiner/co-pilot gives you some help with radios, reading checklists, tuning aids etc) or single pilot (no help from examiner/copilot). If you are tested under 2-pilot rules you are not supposed to excercise IR priviledges when single pilot.
2 pilot helicopters can be flown (without passengers) by a type rating intructor and a non-type rated trainee (otherwise it would be impossible to train/test for the grant of the type rating without a sim). Not totally sure where it says that, but perhaps its that the aircraft are certified to fly with 2 pilots, not 2 type-rated pilots.
HC