There are several threads on here filled with people giving themselves heartburn about this subject.
As I see it, the CAA have a duty to prevent someone with a PPL running any kind of illegal air charter operation. Clearly and for very good reasons, it's absolutely right that people attempting to do this get caught and stopped.
Equally though, a group of work colleagues who go for a jolly in a light aircraft and share the costs in some way are not participating in a commercial flight. I really can't see the CAA getting too excited about it.
Personally, I think that four 'new friends' assembled from their company intranet flying somewhere on a genuine cost share basis, having a lovely day out and helping the pilot keep current is a good thing for the pilot concerned and for aviation in general.