Disable users from changing their display usernames

[CyanGaming]

I thought there was a permission for this, but there doesn't seem to be. Is there anyway I can disable people from changing their display name? I would like users to not be able to change it, but I want moderators and admins to be able to change anyones.

[SychO]

Admin -> Configuration -> Features and Options -> Allow users to edit their displayed name

[Mick.]

...under "General" tab