Once the system contains a full day's data, the Google Analytics View By Hour option appears in a dropdown over the calendar - and voila! You can view your Google analytics hourly reports. The rest of the data is displayed ages before the hourly report option appears.
This information isn't in the help, nor is it noted anywhere I could find by Googling for it. This is bloody annoying. I'm noting it here in the hope that maybe someone else who can't work out where the damn thing is hidden can google and find out here.