Yes when I change themes the toolbar comes back. The design of the rest of my website (casedimage.com) is based around this theme – Wooden Mannequin 1.1.
I did find this article –
https://voodoopress.com/wordpress-3-1-admin-bar-upgrade-issues/
The header/footer solutions didn’t work which is not surprising given the error is in the class-wp-admin-bar.php. But it did give me a solution – to remove the admin toolbar when viewing the site, through editing my options on my user profile. I never used the toolbar from the site anyway but it was handy to see the stats there. Them’s the breaks!
Thanks all for your help.