79. Save to the extent that the company’s constitution provides otherwise, a company may—

(a) make arrangements on the issue of shares for a difference between the shareholders in the amounts and times of payment of calls on their shares;

(b) accept from any member the whole or a part of the amount remaining unpaid on any shares held by him or her, although no part of that amount has been called up;

(c) pay a dividend in proportion to the amount paid up on each share where a larger amount is paid up on some shares than on others; and

(d) by special resolution determine that any portion of its share capital which has not been already called up shall not be capable of being called up except in the event and for the purposes of the company being wound up; upon the company doing so, that portion of its share capital shall not be capable of being called up except in that event and for those purposes.