Thanks for your replies everyone.

It's nice to hear that you think we're on the right track but I'm still not too sure what we are going to do in this particular instance...given that she is waiting for her punishment to be handed down... and has been particularly sulky & horrid today not helping her case, is she?

Any more ideas?
Also, what would you be doing to limit the opportunities for this kind of behaviour? I can't see her being grounded until she's 18...oh but I would like to.....