I am wondering why the synchronisation is one-way rather than bidirectional. My BB calendar events show up on the Gcal webpage, but my Gcal appt's don't show up. On the BB calendar.

Is there a way of syncing in both directions?

Make sure that you have two way sync set up in Google Calendar.

Make sure the right calendar is showing on the BB.

Sorted. Had to go into Google Sync to set the "sync other calendars" option.