[Typo3] [loginUser = *] test for BE users?

[Matthew Manderson]

Regards all,

I want to test for a BE login in the FE. ie when an 'admin' is browsing the 
site I want to show content as they browse only they can see.

In setup:
[loginUser = *] etc. only works for FE users.

Any ideas for a good way to approach it?

Thanks, 
Matthew