Rate of interestU.K.
9. Where the appropriate authority recovers the whole or any part of any extensification payment pursuant to regulation 8, he or it, as the case may be, shall, unless the sum recovered was paid as a result of his or its own error, be entitled in addition to charge and recover on demand interest on the sum recovered at the rate of one per cent above the sterling three months London Interbank Offered Rate on a day-to-day basis for the period from payment to recovery.