ahardist: Sadly it isn't that simple.
You're correct here, after I made this post I went to review my home dashboard and the currency setting hadn't changed on me (even though the chage was reflected in the report designer). While digging deeper I found what the problem is, the reports shown on the home dashboard are generated server side then displayed so its respecting the server's local settings. I was able to see £ when I made the report a PDF instead but that doesn't help with the display on the homepage.
If you want to create the report as a PDF, when customizing your screen, the report object has an option in the settings for the format. If you change this to PDF and trigger it on a button you should be able to see the report generated with your local regional preferences.
~C