found some information from the freedom of information act:
the ECJ determined that a person who holds the nationality of the host Member State and has never exercised their right of free movement and residence do not benefit from the terms of the Free Movement Directive. This is regardless of whether or not they hold dual nationality with another EEA member state. This also means that family members are also unable to derive a right of residence under the Directive on the basis of their relationship to such a national.
3. The intention is to amend the Regulations to reflect the terms of the McCarthy judgment. However, until the Regulations are amended, people who hold British nationality and the nationality of another EEA State must continue to be allowed to rely on that other EEA nationality to benefit from the Regulations.
4. This is because regulation 2 of the Regulations does not currently prevent a British national from relying on their other EEA nationality to come within the scope of the Regulations when they are also a British national. Instead, regulation 2 simply defines EEA national as a national of an EEA and defines an EEA State as:
(a) a member State, other than the United Kingdom,
(b) Norway, Iceland or Liechtenstein, or
(c) Switzerland.
Assessing cases until the EEA Regulations are amended
5. Until such time as regulation 2 is amended, then for all purposes, the current position must be maintained. Caseworkers will need to continue to treat dual British/EEA nationals as though they are EEA nationals when considering an application for documentation under the Regulations. Evidence of the EEA nationality must be provided.
