No proceedings under this Schedule shall be taken against a person if a final decision on the foreign claim has been given in his favour by a court, tribunal or other competent body in the member State in question.

For this purpose a final decision is one against which no appeal lies or against which an appeal lies within a period that has expired without an appeal having been brought.

If he shows that such a decision has been given in respect of part of the claim no proceedings under this Schedule shall be taken in relation to that part.