Basically I thought that the regional settings of a report generated using Report Builder 2.0 on a MS SQL Server 2008 instance were dependent on either the server or the client machine.  Realised that this was actually specified in the report. Here's a quick note on how to set Dates and Times used in parameter fields to UK format (dd/MM/yyyy).

You can override this in the report by:

1. Go to Design
2. Select the View tab
3. Check that the "Properties" pane is displayed/ticked
4. Change Language under Report Properties > Localization to en-GB
5. Save the report and test.