I'm an enemy of Britannia, but I'm still a citizen, aren't I?

To be succinct, no.  Those who are declared enemies of Britannia are no longer considered citizens.  To some, this may seem an obvious statement, barely worth merit of mentioning herein, however, history has shown us we need be clear on this matter.

Enemies of Britannia are not afforded the rights commonly associated with citizenship.  This means that enemies may not sit in on meetings of the High Council (unless prior arrangement has been made with the Grand Marshall of Virtue, and generally there must be purpose for such an arrangement, not simply to sit in on meetings).  Enemies of Britannia are not afforded protection from other enemies of Britannia.  Even that sounds obvious, but we have had declared enemies approach the Council to complain that other enemies have attacked them.

This is not to say that being an enemy of Britannia subjects you to unvirtuous acts.  Britannia does not support "war crimes" and will investigate any claims of such to the utmost degree.