(1)Where the declaration of a new standard rate or, as the case may be, the determination of a new locally determined rate, affects the rate of interest chargeable under section 219 by a local authority the authority shall, as soon as practicable after such declaration or determination, serve in respect of each of its variable interest home loans a notice on the borrower which shall, as from the appropriate day—
(a)vary the rate of interest payable by him; and
(b)where, as the result of the variation, the amount outstanding under the advance or security would increase if the periodic repayments were not increased, increase the amount of the periodic repayments to such an amount as will ensure that the said outstanding amount will not increase.
(2)In subsection (1), “the appropriate day” means such day as shall be specified in the notice, being—
(a)in the case of a new standard rate, a day not less than 2 weeks, nor more than 6 weeks, after service of the notice; and
(b)in the case of a new locally determined rate, the first day of the relevant period of 6 months.