If anyone has the same problem in the future I have found a way around it.
When configuring the block on the default dashboard, in the 'Where this block appears' section, I just set the 'Select pages' to 'Any page matching the above', with the page above being Dashboard.
Seems obvious now, there's probably a better way of doing it with the code (which I'd be interested to hear of), but this works for me at the moment.
Simon