(7) Where the amount of any assessment is reduced as a result of any reference to the High Court, the amount, if any, over- paid as estate duty shall be refunded with such interest as the Controller may allow unless the High Court, on intimation being given by the Controller within thirty days of the receipt of the result of such reference that he intends to ask for leave to appeal to the Supreme Court, makes an order authorising the Controller to postpone payment of such refund until the disposal of the appeal in the Supreme Court.