XF 1.5 Fixed banner unless user sets custom banner

[MagicalMidge]

Wondering if there is a way I can force xen to use my set userbanner text (for a particular usergroup the user is part of) unless they change it in there profile page, and if they do change it, it would over ride there user groups preset message.

Any help would be appreciated as im at a bit of a loss on this one

Regards,
Matthew